The LS1034 CRC cell line turned out to be a unique model for functional studies due to (i) the irreversible loss of engraftment potential accompanying CD133-negativity in vivo but not in vitro, and (ii) the de novo expression of CD44, and in particular of CD44v8-10, correlating with highest tumorigenicity in vivo. This evidence concerns the gene PROM1 and colorectal carcinoma.