Depending on where you started your research career, perhaps in the tissue culture laboratory, or producing a mouse model, or indeed in the clinic, your perception of which biological changes are important in tumorigenesis is probably skewed in a specific direction. Despite this, we can still overlook basic biological facts that were on our radars during college but have been forgotten amid the complexity of tumour biology and the specialization that research requires.

One good example is the effect that the stiffness of a given tissue has on the cells within the tissue, something that is addressed by Valerie Weaver and colleagues on page 108 of this issue. Cells respond to a variety of physiological mechanical stimuli by altering their shape, function or gene expression profiles. Such changes seem to be important in cancer biology — breast tumours are significantly stiffer than the normal surrounding breast tissue. Thus, understanding how cells sense mechanical changes in both normal and tumour tissue might identify new pathways that can be exploited in the clinic.

We also tend to forget that cells not only respond to stimuli by altering morphology and gene expression, but also by secreting particular factors. On page 81 Thomas Kuilman and Daniel Peeper outline the factors that are secreted by senescent cells and how these might function to promote senescence and limit tumorigenesis. They also speculate on whether the production of specific secreted factors might alert other cells within the tissue to the need to enter a senescent state.

Although it is important to focus in on the function of a specific protein or gene during cancer development, it is also crucial to place this in the wider context of changes that occur in the tissue as the tumour develops.