PROS1 and chondrosarcoma: These antiapoptotic proteins and P-glycoprotein are two independent chemoresistance mechanisms in chondrosarcoma cells since targeting antiapoptotic proteins did not have any effect on the activity, mRNA expression level and protein expression level of P-glycoprotein (Figure 4A, B, 5D and 6) and targeting P-glycoprotein did not change the expression level of antiapoptotic proteins, either (Figure 6).