p63RhoGEF-mediated formation of a single polarized lamellipodium is required for chemotactic migration in breast carcinoma cells.

Short hairpin RNAs targeting 66 Rho-GEFs were screened for inhibition of chemotaxis. Six Rho-GEFs (p63RhoGEF, Trio, Duet, Net1, Frabin/Fgd4, and AAH33666) were found to be required for the serum-induced chemotactic migration of MDA-MB-231 human breast carcinoma cells. Knockdown of p63RhoGEF suppressed serum-induced RhoA activation and chemotaxis and caused the aberrant formation of multiple lamellipodial protrusions after serum stimulation while control cells formed a single polarized lamellipodium. These results indicate that p63RhoGEF plays a crucial role in serum-induced chemotaxis by limiting lamellipodial protrusion to one direction via RhoA activation.