proline-serine-threonine phosphatase interacting protein 1; Involved in regulation of the actin cytoskeleton. May regulate the WAS actin-bundling activity. Bridges the interaction between ABL1 and PTPN18 leading to the ABL1 dephosphorylation. May play a role as a scaffold protein between PTPN12 and WAS and allows PTPN12 to dephosphorylate WAS. Has the potential to physically couple CD2 and CD2AP to WAS. Acts downstream of CD2 and CD2AP to recruit WAS to the T-cell-APC contact site so as to promote the actin polymerization required for synapse induction during T-cell activation (By simi [...] (416 aa)