However, T3 has opposite effects on hepatocellular carcinoma cells (HCCs) [256] and colon cancer cells, probably by stimulating the expression of P-glycoprotein/multidrug resistance-1 (P-gp/MDR1), a member of the ATP-binding cassette-containing (ABC) transporters that mediate xenobiotic extrusion from cells [257]. The gene discussed is ABCB1; the disease is malignant colon neoplasm.