They then went on to show significant synergy when MK-1775 was added to gemcitabine therapy in four sarcoma cell lines, U2O5 (osteosarcoma), MG63 (osteosarcoma), A673 (Ewing sarcoma), and HT-1080 (fibrosarcoma), despite two being p53 wild type (U2O5 and HT-1080) [104]. Here, TP53 is linked to osteosarcoma.