More significantly, results of erdafitinib inhibiting the drug efflux function of ABCB1 (Figure 2) and improving the susceptibility of KB-V-1 cells to drug-induced apoptosis (Figure 4) indicate that erdafitinib reverses ABCB1-mediated multidrug resistance by restoring the cytotoxicity of ABCB1 substrate anticancer drugs in these multidrug-resistant cancer cells. The gene discussed is ABCB1; the disease is cancer.