Darmanis, S. et al. Cell Rep. 14, 380–389 (2016).

Methods that characterize RNA and DNA at the single-cell level have attracted a great deal of attention recently, yet protein measurements also provide important information about cell state and function. Darmanis et al. describe a method for measuring both RNA and protein in multiplex from single cells. Cells are sorted into microwell plates, and the lysate is split in two; one fraction undergoes quantitative RT-PCR, and the other undergoes a proximity extension assay (PEA). PEA uses two different oligonucleotide-linked antibodies to bind a given protein target, forming a bridge that allows a PCR-based readout; the need for two antibodies lends high specificity. The authors developed 75 PEAs for proteins relevant to glioblastoma and profiled RNA and protein to assess the effects of BMP4 treatment on early-passage patient-derived glioblastoma cells.