ARHGDIB and Familial prostate cancer: Another potential therapeutic agent, namely atrasentan (Figure 6B), which is currently in Phase III trials for stage IV prostate cancer, was shown to antagonize endothelin 1, a down-stream molecules of metastasis of RhoGDI2, mimicking the role of RhoGDI2 and reducing T24T cell metastases in animal models [164, 165].