Fig. 8. Model for FAK-mediated FA dynamics. (A) FAK exists in equilibrium between two compartments: in assembled FAs and in cytosol. Increasing k_on or k_off will either stabilize or disassemble FAs. (B) In FAs, FAK is phosphorylated by cis/trans activation before leaving the FA compartment. (C) Decreasing k₃, for example by expression of mutant Y397F-FAK, will lead to accumulation of non-phosphorylated FAK at FAs and thus a greater k₂ (consistent with the shorter recovery half-time for Y397F-FAK/YCam compared to FAK/YCam), and in turn, to a decrease in FA disassembly.