PROM1 and melanoma: With the intent to target cell populations with innate drug resistance and potential metastatic activity, the concomitant expression of CXCR4 and CD133 was evaluated in the NCI 60 tumor cell line panel comprising cell lines derived from hematopoietic malignancies and several solid tumors (lung cancer, central nervous system (CNS), colon, breast, ovarian, and prostate cancer and melanoma) extensively characterized for patterns of gene expression6, 7.