ABCC1 and osteosarcoma: Targeting ABCB1/ABCC1 with the inhibitor CBT-1 (Tetrandrine) in chemotherapy-resistant osteosarcoma cell lines was able to restore sensitivity to doxorubicin as well as second-line therapy drugs etoposide, Taxotere, and vinorelbine, making this an interesting option in the treatment of refractory or recurrent osteosarcoma [317].