Stimulation of extension

However, there is also stimulation of turnover of old adhesion sites. One possible mechanism for stimulated removal of old adhesion sites is via extracellular signal-regulated kinase (ERK) activation of calpain [249], followed by calpain-mediated cleavage of adhesion proteins such 

Mechanisms of contraction for mesenchymal cells may be more dependent on formation of stress fibers and focal contacts than on the cortical contraction mechanisms seen in Dictyostelium [195]. Receptor tyrosine kinases can stimulate increased myosin light chain phosphorylation via rho activation as a mechanism for contraction. Alternatively, increased contraction may follow formation of new focal contacts, possibly via focal adhesion kinase and src-based mechanisms [212]. This would be consistent with the temporal sequence of events that are observed, with contraction being a late step that should follow formation of new focal contacts. 

---