WASP, as the name suggests, was initially identified as a defective protein from Wiskott-Aldrich syndrome patients.367 Decreased IL-2 production, calcium flux, and defective actin polymerization were seen in VAV−/− animals, and a similar phenotype was observed in T cells from WASP patients and murine cells from WAS−/− animals.368,369 This could be explained by the fact that WASP normally exists in an autoinhibited state in resting T cells, where the GTPase-binding domain interacts with the C-terminus that contains the Arp2/3 complex responsible for actin polymerization. The gene discussed is WAS; the disease is Wiskott-Aldrich syndrome.