Additionally, overexpression of the CD133+ CD44+ population in HCC cells promotes stem/progenitor cell properties, including extensive proliferation, self-renewal, differentiation, and increased resistance to chemotherapeutic agents, via upregulation of ABC transporters (ABCB1, ABCC1, and ABCG2) [21]. The gene discussed is ABCB1; the disease is hepatocellular carcinoma.