WASP is phosphorylated on Tyr291 (Cory et al. 2002) and N-WASP (WASL) on Tyr256 (Wu et al. 2004) by Src family of tyrosine kinases and this phosphorylation may release the autoinhibitory intramolecular interactions. The phosphorylation seems to be enhanced by the activation of CDC42. WASP phosphorylation and binding of CDC42 have a synergistic effect on the activation of the ARP2/3 complex (Takenawa & Suetsugu 2007). In N-WASP, the phosphorylation may reduce its nuclear translocation and may sustain it in its functional site in the cytoplasm (Wu et al. 2004).