Moreover, OLE and the combined treatment also obviously caused the upregulation of cleaved caspase-9 and the downregulation of Bcl-2, whereas DDP alone only slightly increased the activation of caspase-9 in 143B and U-2OS cells and did not alter the expression of Bcl-2 in any osteosarcoma cells (Fig. 2c). Here, CASP9 is linked to osteosarcoma.