The G12/13 family is probably the least well characterized subtype, partly because G12/13 coupling is difficult to determine when compared with the other subtypes which predominantly rely on assay technologies that measure intracellular calcium. The G12/13 family are best known for their involvement in the processes of cell proliferation and morphology, such as stress fiber and focal adhesion formation. Interactions with Rho guanine nucleotide exchange factors (RhoGEFs) are thought to mediate many of these processes. (Buhl et al.1995, Sugimoto et al. 2003). Activation of Rho or the regulation of events through Rho is often taken as evidence of G12/13 signaling. Receptors that are coupled with G12/13 invariably couple with one or more other G protein subtypes, usually Gq.