Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Non-genetic origins of cell-to-cell variability in TRAIL-induced apoptosis


In microorganisms, noise in gene expression gives rise to cell-to-cell variability in protein concentrations1,2,3,4,5,6,7. In mammalian cells, protein levels also vary8,9,10 and individual cells differ widely in their responsiveness to uniform physiological stimuli11,12,13,14,15. In the case of apoptosis mediated by TRAIL (tumour necrosis factor (TNF)-related apoptosis-inducing ligand) it is common for some cells in a clonal population to die while others survive—a striking divergence in cell fate. Among cells that die, the time between TRAIL exposure and caspase activation is highly variable. Here we image sister cells expressing reporters of caspase activation and mitochondrial outer membrane permeabilization after exposure to TRAIL. We show that naturally occurring differences in the levels or states of proteins regulating receptor-mediated apoptosis are the primary causes of cell-to-cell variability in the timing and probability of death in human cell lines. Protein state is transmitted from mother to daughter, giving rise to transient heritability in fate, but protein synthesis promotes rapid divergence so that sister cells soon become no more similar to each other than pairs of cells chosen at random. Our results have implications for understanding ‘fractional killing’ of tumour cells after exposure to chemotherapy, and for variability in mammalian signal transduction in general.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Figure 1: The time-to-death is highly correlated between HeLa sister cells, but correlation decays as a function of time since division.
Figure 2: Endogenous variation in the concentrations of apoptotic regulators is sufficient to explain variability in Td.
Figure 3: A single time-dependent process upstream of MOMP predicts the time-to-death.
Figure 4: No single protein predicts T d under normal conditions but overexpression can increase predictability.


  1. Blake, W. J., Kærn, M., Cantor, C. R. & Collins, J. J. Noise in eukaryotic gene expression. Nature 422, 633–637 (2003)

    Article  ADS  CAS  Google Scholar 

  2. Colman-Lerner, A. et al. Regulated cell-to-cell variation in a cell-fate decision system. Nature 437, 699–706 (2005)

    Article  ADS  CAS  Google Scholar 

  3. Elowitz, M. B., Levine, A. J., Siggia, E. D. & Swain, P. S. Stochastic gene expression in a single cell. Science 297, 1183–1186 (2002)

    Article  ADS  CAS  Google Scholar 

  4. Golding, I., Paulsson, J., Zawilski, S. M. & Cox, E. C. Real-time kinetics of gene activity in individual vacteria Cell . 123, 1025–1036 (2005)

  5. McAdams, H. H. & Arkin, A. Stochastic mechanisms in gene expression. Proc. Natl Acad. Sci. USA 94, 814–819 (1997)

    Article  ADS  CAS  Google Scholar 

  6. Ozbudak, E. M., Thattai, M., Kurtser, I., Grossman, A. D. & van Oudenaarden, A. Regulation of noise in the expression of a single gene. Nature Genet. 31, 69–73 (2002)

    Article  CAS  Google Scholar 

  7. Rosenfeld, N., Young, J. W., Alon, U., Swain, P. S. & Elowitz, M. B. Gene regulation at the single-cell level. Science 307, 1962–1965 (2005)

    Article  ADS  CAS  Google Scholar 

  8. Chang, H. H., Hemberg, M., Barahona, M., Ingber, D. E. & Huang, S. Transcriptome-wide noise controls lineage choice in mammalian progenitor cells. Nature 453, 544–547 (2008)

    Article  ADS  CAS  Google Scholar 

  9. Feinerman, O., Veiga, J., Dorfman, J. R., Germain, R. N. & Altan-Bonnet, G. Variability and robustness in T cell activation from regulated heterogeneity in protein levels. Science 321, 1081–1084 (2008)

    Article  ADS  CAS  Google Scholar 

  10. Sigal, A. et al. Variability and memory of protein levels in human cells. Nature 444, 643–646 (2006)

    Article  ADS  CAS  Google Scholar 

  11. Albeck, J. G. et al. Quantitative analysis of pathways controlling extrinsic apoptosis in single cells. Mol. Cell 30, 11–25 (2008)

    Article  CAS  Google Scholar 

  12. Albeck, J. G., Burke, J. M., Spencer, S. L., Lauffenburger, D. A. & Sorger, P. K. Modeling a snap-action, variable-delay switch controlling extrinsic cell death. PLoS Biol. 6, 2831 (2008)

    Article  CAS  Google Scholar 

  13. Geva-Zatorsky, N. et al. Oscillations and variability in the p53 system. Mol. Syst. Biol. 2, 2006.0033 (2006)

    Article  Google Scholar 

  14. Goldstein, J. C., Kluck, R. M. & Green, D. R. A single cell analysis of apoptosis. Ordering the apoptotic phenotype. Ann. NY Acad. Sci. 926, 132–141 (2000)

    Article  ADS  CAS  Google Scholar 

  15. Lahav, G. et al. Dynamics of the p53–Mdm2 feedback loop in individual cells. Nature Genet. 36, 147–150 (2004)

    Article  CAS  Google Scholar 

  16. Kaufmann, B. B., Yang, Q., Mettetal, J. T. & van Oudenaarden, A. Heritable stochastic switching revealed by single-cell genealogy. PLoS Biol. 5, e239 (2007)

    Article  Google Scholar 

  17. Rando, O. J. & Verstrepen, K. J. Timescales of genetic and epigenetic inheritance. Cell 128, 655–668 (2007)

    Article  CAS  Google Scholar 

  18. Chaudhary, P. M., Eby, M., Jasmin, A., Bookwalter, A., Murray, J. . & Hood, L. Death receptor 5, a new member of the TNFR family, and DR4 induce FADD-dependent apoptosis and activate the NF-κB pathway. Immunity 7, 821–830 (1997)

    Article  CAS  Google Scholar 

  19. Fuentes-Prior, P. & Salvesen, G. S. The protein structures that shape caspase activity, specificity, activation and inhibition. Biochem. J. 384, 201–232 (2004)

    Article  CAS  Google Scholar 

  20. Li, H., Zhu, H., Xu, C. & Yuan, J. Cleavage of BID by caspase 8 mediates the mitochondrial damage in the Fas pathway of apoptosis. Cell 94, 491–501 (1998)

    Article  CAS  Google Scholar 

  21. Luo, X., Budihardjo, I., Zou, H., Slaughter, C. & Wang, X. Bid, a Bcl2 interacting protein, mediates cytochrome c release from mitochondria in response to activation of cell surface death receptors. Cell 94, 481–490 (1998)

    Article  CAS  Google Scholar 

  22. Youle, R. J. & Strasser, A. The BCL-2 protein family: opposing activities that mediate cell death. Nature Rev. Mol. Cell Biol. 9, 47–59 (2008)

    Article  CAS  Google Scholar 

  23. Wagner, K. W. et al. Death-receptor O-glycosylation controls tumor-cell sensitivity to the proapoptotic ligand Apo2L/TRAIL. Nature Med. 13, 1070–1077 (2007)

    Article  CAS  Google Scholar 

  24. Cohen, A. A. et al. Dynamic proteomics of individual cancer cells in response to a drug. Science 322, 1511–1516 (2008)

    Article  ADS  CAS  Google Scholar 

  25. Barkai, N. & Leibler, S. Robustness in simple biochemical networks. Nature 387, 913–917 (1997)

    Article  ADS  CAS  Google Scholar 

  26. Ashkenazi, A. & Herbst, R. S. To kill a tumor cell: the potential of proapoptotic receptor agonists. J. Clin. Invest. 118, 1979–1990 (2008)

    Article  CAS  Google Scholar 

  27. Berenbaum, M. C. In vivo determination of the fractional kill of human tumor cells by chemotherapeutic agents. Cancer Chemother. Rep. 56, 563–571 (1972)

    CAS  PubMed  Google Scholar 

  28. Debnath, J., Muthuswamy, S. K. & Brugge, J. S. Morphogenesis and oncogenesis of MCF-10A mammary epithelial acini grown in three-dimensional basement membrane cultures. Methods 30, 256–268 (2003)

    Article  CAS  Google Scholar 

  29. Boatright, K. M., Deis, C., Denault, J. B., Sutherlin, D. P. & Salvesen, G. S. Activation of caspases-8 and -10 by FLIPL . Biochemical journal 382, 651–657 (2004)

    Article  CAS  Google Scholar 

Download references


We thank D. Flusberg, S. Govind, L. Kleiman, A. Letai, B. Millard, R. Milo, T. Norman, J. Paulsson and R. Ward for their help. This work was supported by National Institute of Health (NIH grants) GM68762 and CA112967.

Author information

Authors and Affiliations


Corresponding author

Correspondence to Peter K. Sorger.

Ethics declarations

Competing interests

P.K.S. is a Director of Applied Precision Inc., manufacturers of the microscopes used in this study.

Supplementary information

Supplementary Information

This file contains Supplementary Figures 1-9 with Legends, Supplementary Tables 1-2 and a Supplementary Reference. (PDF 2978 kb)

PowerPoint slides

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Spencer, S., Gaudet, S., Albeck, J. et al. Non-genetic origins of cell-to-cell variability in TRAIL-induced apoptosis. Nature 459, 428–432 (2009).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing