PPIG and nasopharyngeal carcinoma: We reported that pseudogenes from cytochrome P450 (CYP) family, such as CYP2F2P, CYP2G1P, CYP4F24P, CYP2B7P and CYP2G2P were significantly down-regulated in NPC compared to paracancerous tissues, while IGHV1OR15–2, IGHV3–11, FCGR1CP and IGHV3–69-1 belonging to Fc gamma receptors were significantly up-regulated.