XIAP and colitis: Despite the similar susceptibility between Socs1f/fLckCre Treg cells36 and Xiap−/− Treg cells to generate IFN-γ and their defective abilities to inhibit colitis (Fig. 1g and h), Treg-specific-knockout of SOCS1 (Socs1f/fFoxp3Cre) generates Treg cells that can still suppress colitis in Rag2−/− mice55.