MAPK8 and neoplasm: Induce G2/M phase cell cycle arrest, down-regulate Bcl-2 as well as up-regulate Bax, P53 and cytochrome C, induce apoptosis through activation of the caspase pathway, attenuate Nrf2/Akt and activative of the JNK and P38-MAPK pathways, and improve the anti-tumor efficacy of cisplatin (DDP)