PGP and ovarian cancer: It has been found that when ROS levels are maintained in a certain degree of equilibrium with antioxidants, a certain concentration of ROS is maintained in the cells, and this may promote the expression of multidrug resistance genes (e.g., P-glycoprotein (P-gp) and multidrug resistance protein 1 (MRP1)) in ovarian cancer cells, which ultimately leads to the formation of multidrug resistance [50].