Figure 11.

Proposed mechanism for how αvβ3 integrin signaling could be mediating fibronectin matrix assembly in TM cells. Recent studies by Schiller et al.⁷⁶ suggest that there are alternative ways in which stress fibers can be assembled by integrin signaling. Signaling from α5β1 integrins can activate a RhoA/ROCK-dependent signaling pathway that results in myosin phosphorylation. In contrast, αvβ3 integrin signaling can use a separate ROCK-independent pathway that utilizes RhoA/mDia, which promotes enhanced F-actin polymerization that is required for the formation of stress fibers. In addition, these actin filaments are necessary for the formation of fibrillar adhesions that are the sites of fibronectin fibrillogenesis.⁷⁷ Together these two processes lead to stronger contractile forces that could ultimately lead to the enhanced fibronectin matrix assembly demonstrated by CAβ3 cells.