Taken together, the results suggest that CRMP4 down-regulates MMP-9 expression and inhibits Rac1 GTPase by enhancing phosphorylation of Rac1 and Akt through direct interaction with Rac1 and Akt, eventually leading to suppression of prostate cancer invasion and metastasis (Figure 5h). Here, RAC1 is linked to prostate carcinoma.