TFRC and colitis: As early as three weeks after the initial tamoxifen treatment, Tfrc iKO mice showed signs of colitis, including inflammatory cell infiltration (Supplementary Fig. S8g), slower body weight gains (Fig. 4h), and shortening of the colon (Fig. 4 i, j), while no obvious inflammation was observed in other organs (e.g., lung, liver, and kidney, Supplementary Fig. S8g).