PAK1 and breast cancer: Pak1 is required for KIF5B‐mediated transport of a large WAVE2 protein complex toward membrane protrusions in response to hepatocyte growth factor in breast cancer cells.11, 36 Also, stathmin/Op18 is associated with hepatocyte growth factor‐induced WAVE2 transport to membranes and the formation of cell protrusions.37 The WAVE2‐Arp2/3 complex induces the nucleation of actin assembly, thereby leading to the formation of cell protrusions.5, 38 Thus, WAVE2 is involved in protrusion formation and promotes cell motility and invasion.