Hepatocellular carcinoma and multidrug resistance: Past, present and new challenges for therapy improvement

Figure 4 Mechanisms of multidrug resistance in cancer cells. (1) Active drug efflux by drug transporters, such as Pgp, multidrug resistance-associated protein, and breast cancer resistance protein; (2) Loss of cell surface receptors and/or drug transporters or alterations in membrane lipid composition; (3) Compartmentalization of the drug in cellular vesicles; (4) Altered/increased drug targets; (5) Alterations in cell cycle; (6) Increased drug metabolism/enzymatic inactivation; (7) Active damage repair; and (8) Inhibition of apoptosis. Reprinted with permission from ref. [181].