Serial transplantation of 50 ESA+CD44+ or ESA+CD44+CD166+ cells from tumors in CPA- versus vehicle-treated control mice resulted in secondary tumors with roughly equal frequency (Table 1), which when considered in conjunction with previous observations suggest that CoCSC are more frequent within tumors exposed to CPA chemotherapeutic regimens and are unaffected in their ability to fuel tumor growth. This evidence concerns the gene CD44 and neoplasm.