In addition, SOX9, a key regulatory factor for intestine development, is identified as a marker for intestinal stem/progenitor cells, and it is also associated with tumorigenesis and cancer progression.[51] In the present study, we found that Selenoi deficiency resulted in a reduction of Sox9+ stem/progenitor cells in colitis and a subsequent decrease in tumors from the AOM‐DSS colorectal cancer mouse model. Here, SELENOI is linked to colitis.