PGP and liver cancer: In contrast, icaritin targets MDR1 and downregulates the protein expression of P-gp in liver cancer (Hep G2/ADR) cells, meanwhile, it decreases the mRNA and protein levels of MDR1 and MRP1 in osteosarcoma (MG-63/DOX) cells to sensitize them to adriamycin and doxorubicin, respectively [717, 718].