ARHGEF16 and breast carcinoma: ARHGEF16 (also known as Ephexin4, GEF16, or NBR) is a GEF that can activate RhoG, Rac1, and Cdc42 proteins of the Rho GTPase family [32–34] and thereby promote migration and resistance to apoptosis of breast cancer cells [35] independent of Ephrin signaling.