PGP and osteosarcoma: One of the most prominent and well-characterized mechanisms of multi-drug resistance (MDR) in osteosarcoma is the prevalence of the multidrug resistance 1 gene (MDR1), which produces p-glycoprotein (p-gp), or the ATP-binding cassette B1 (ABCB1) and actively pumps drugs such as doxorubicin, cisplatin, and other chemotherapies outside of the cell [9].