The protein encoded by this gene binds to the cytoplasmic tail of CD2, an effector of T cell activation and adhesion, negatively affecting CD2-triggered T cell activation. The encoded protein appears to be a scaffold protein and a regulator of the actin cytoskeleton. It has also been shown to bind ABL1, PTPN18, WAS, CD2AP, and PTPN12. Mutations in this gene are a cause of PAPA syndrome. [provided by RefSeq, Jul 2008]