MAPK8 and cancer: Many reports have highlighted that celastrol is becoming an effective, safe and desirable approach to the treatment of cancers.6, 7, 8, 9, 10, 11, 12 Our results presented here confirm that celastrol could inhibit proliferation of human osteosarcoma in vitro and in vivo through G2/M arrest, apoptosis and autophagy mediated by the ROS/JNK signaling pathway.