PROM1 and colonic neoplasm: To ask whether PTPRK could participate in the regulation of CD133‐mediated colon cancer progression, human colon cancer HT‐29 cells, which express endogenous CD133 (Fig. S1A), were infected with lentiviral vectors carrying shRNA against PTPRK (shPTPRK#1 or shPTPRK#2) or with the empty vector (pLKO).