CD274 and ovarian cancer: In addition, we also did not detect any expression of PD-1 and OX40 molecules and their respective ligands PD-L1/PD-L2 and OX40L on the surface of ID8 ovarian cancer cells (data not shown), excluding the possibility that inhibition of ID8 tumor growth in vivo is directly mediated by anti-PD-1 or anti-OX40 mAb.