SH2D1A and lymphoma: SAP is involved in the function of cytotoxic lymphocytes and is a key regulator of normal immune function in T and NK cells, as well as the of NK‐cell apoptosis.73, 74, 75 Mutations that disrupt the SAP protein impair proper signalling to induce immune response toward viral (EBV) infection and led to the development of lymphomas due to defective lymphocytes apoptosis.