RAC1 and diabetes mellitus: Immunohistochemical analysis using anti-Rac1 monoclonal antibody showed that the immunostaining of Rac1 occurred in the retinal vasculature, including the ECs and pericytes, and in the outer plexiform layer (OPL), the inner nuclear layer (INL), the inner plexiform layer (IPL) and the ganglion cell layer (GCL) of the rat retinas; the Rac1 immunoreactivity was significantly increased in the retinas at 12 weeks after the induction of diabetes compared with that in the controls (Fig. 3B).