CXCR4 and neoplasm: Furthermore, a study of tumorigenic CD133/CXCR-4-co-expressing cells, contradicting a general conviction that CD133 is not a marker of renal CSCs, showed a promoting effect of Sunitinib-induced hypoxia in tumor perinecrotic areas on the number of these cells, thus, Sunitinib was able to generate resistance to its own therapeutic effect [86].