FIG. 6.

Rac directly interacts with Nox, NOS, and SOD. Rac isoforms have been shown to directly enhance the activities of NOS and Nox isoforms (23, 45, 48). In several Nox isoforms, Rac must interact with the p67 subunit (and possibly flavocytochrome b558) for Nox to convert O₂ to O₂^•− (7, 23). In addition to evidence that Rac indirectly stimulates NOS activity, Rac1 has been shown to increase eNOS and nNOS activity through direct interaction, aiding in the conversion of O₂ to NO (45, 48). Finally, recent data show that Rac1 directly interacts with SOD1 in a nucleotide- and redox-dependent manner (16). eNOS, endothelial NOS; nNOS, neuronal NOS; O₂^•−, superoxide; SOD, superoxide dismutase.