Although CD133 has recently been recognized as a potential stem cell marker capable of identifying a tumor-initiating population in solid tumors, the consistent overexpression of CD133 cells in conjunction with other melanoma stem cell markers among patients with high-risk primary or recurrent melanoma has not yet been clearly established and no preferential CD133 ligands or connections with signaling pathways have been elucidated. The gene discussed is PROM1; the disease is melanoma.