Figure 3. Proposed model of balanced Dia1 and ROCK activities in cell-cell cohesion. Under normal physiological conditions, the two Rho effectors work in synergy to align and maintain a circumferential actomyosin bundle, and to promote the formation of mature belt-like endothelial AJs. However, loss of Dia1 signaling, and/or increased signaling via ROCK promotes the transition of belt-like AJs to punctate AJs. This transition is accompanied by a shift from the parallel, circumferential actomyosin bundles into unorganized, radially attached actin stress fibers that exert contractile forces able to disrupt junction stability.