C6 urea ceramide is an inhibitor of neutral ceramidase.1 It increases total ceramide levels in wild-type mouse embryonic fibroblasts (MEFs) and in HT-29 colon cancer cells but not in MEFs lacking neutral ceramidase. It inhibits proliferation of, and induces apoptosis and autophagy in HT-29, but not non-cancerous RIE-1, cells when used at concentrations of 5 and 10 μM. C6 urea ceramide decreases total β-catenin, increases phosphorylated β-catenin, and induces colocalization of β-catenin with the 20S proteasome in HT-29 and HCT116, but not RIE-1, cells. It reduces tumor growth and increases C16, C18, C20, and C24 ceramide levels in tumor tissue in an HT-29 mouse xenograft model when administered at doses of 1.25, 2.5, and 5 mg/kg for five days.