MAPK8 and neoplasm: Notch-active tumor cells recruit hemocytes carrying the tumor necrosis factor–α (TNF-α) homolog Eiger to the tumor microenvironment (TME), activating the c-Jun N-terminal kinase (JNK) pathway in tumor cells, instigating the sexually dimorphic up-regulation of cytokine Unpaired 2 (Upd2).