SMPD2 and colorectal carcinoma: We therefore treated fibroblasts (18Co and CAFs) with GW4869, a specific neutral sphingomyelinase inhibitor [19] that blocks exosome release (Supplementary Figures S4b and c), and then obtained the CM (exosome-depleted CM), which was added to CD133−/lo CRC cells treated with either 5-Fu or OXA.