It is not hard to imagine that cells, in general, respond to not only their chemical environment, but also their mechanical environment. Indeed, cells and molecules are also physical objects under the influence of mechanical forces. But what are these mechanical forces? What are their magnitudes? What roles do they have on cell behaviours? And how do cells sense and respond to them? Systematic and quantitative investigations of these questions began two decades ago and was propelled by two factors. One was the maturation of tools and methodologies brought about by intensive interdisciplinary collaborations. The second was the realization that genes and molecules might not explain everything. The paper that we will discuss in this lecture is an important study that came out at the rising phase of mechanobiology. By using cutting-edge technologies, the authors of this study revealed a striking phenomenon that the substrate elasticity of the multipotent mesenchymal stem cells could direct lineage specifications of these cells. Before the lecture, I would like you to have a read of the paper, but do not feel too bothered if you cannot completely understand its many details. Instead spend some thoughts on: (1) What was the key question? (2) What technologies enabled the authors to address this question? (3) What are the next important questions this study opened up to?

The paper we will read and discuss is:

Engler et al., 2006, Cell 126(4): 677-89 "Matrix elasticity directs stem cell lineage specification".