PROM1 and colorectal carcinoma: To assess whether fibroblast-derived paracrine factors are involved in CRC progression, the CRC cell line KM12C was cultured in the CM of two human fibroblast cell lines, MRC-5, and WS1, and assessed for a number of CIC properties including invasive capacity, epithelial-mesenchymal transition (EMT), β-catenin translocation, sphere formation, and drug resistance; these functional assays have been shown to be more relevant to disease progression than CIC markers such as CD133 (28).