Cells typically grow in a dense protein jungle known as the extracellular matrix (ECM), which provides structural and biochemical support [38]. Additionally, the ECM allows cells to sense elasticity and stiffness in order to get a [pun-intended] “feel” for the environments they are in. Work from Helen Blau and others has shown a vital importance for the stiffness and elasticity of the ECM substrate on skeletal muscle self-renewal and differentiation [39, 40]. The same is true for other cell types, which is an often over-looked fact that cell biologists of the future will ask, “what were they doing?” So why is this relevant?