SLC9A3 and neoplasm: This is the first report conclusively demonstrating that colorectal cancer is associated with the loss of NHE3 expression and that this has functional consequence for tumor growth, mucosal inflammation, gut microbiota in ApcMin/+NHE3−/− mice, and that NHE3 deficiency promotes the intrinsic proliferative, apoptotic, and adhesive properties of colorectal cancer cells.