MAPK8 and osteosarcoma: Figure 7c shows that celastrol increased levels of cleaved caspase-3, LC3B-II and phospho-JNK. Immunohistochemistry demonstrated the increase in mean areas that stained positively for cleaved caspase-3 and phospho-JNK in celastrol-treated tumor tissues, which was quantified by IPP software in terms of mean optical density (MOD) (Figures 7d and e). All the results reveal that celastrol inhibits growth of osteosarcoma in vivo with low levels of toxicity.