The role of mechanics in TGF-β activation. TGF-β is released in latent form, enclosed within the latency-associated peptide (LAP) as part of the TGF-β latent complex. Cell surface integrins, which connect to cytoplasmic actins at the site of focal adhesions, bind to LAP. As shown by Hinz and colleagues [36, 37], on soft surfaces (left) there is minimal resistance to cell generated tension and the complex remains latent. On stiff surfaces (right), there is significant resistance to cell-generated tension, this tension increases, and the LAP is pulled open, releasing active TGF-β.