To further explore whether PrPC controls cancer stem cell properties in drug-resistant CRC cells, we investigated the formation of cancer spheres and the expression of cancer stem cell markers, including ALDH1A, Nanog, and Oct4 in 5FU-resistant CRC cells (SNU-C5/5FUR) and oxaliplatin-resistant CRC cells (SNU-C5/OXR). This evidence concerns the gene PRNP and cancer.