Activator of apoptosis, with grim and rpr, that acts on the effector Dredd (PubMed:9740659, PubMed:22615583). Seems to act genetically upstream of baculoviral anti-apoptotic p35 (PubMed:7622034). Blocks Diap2 from binding and inactivating the effector caspase Drice (PubMed:18166655). Might regulate apoptosis downstream of Clbn/NEMF (PubMed:22964637). Interacts with Diap2 (via BIR2 and BIR3 domains). Expression coincides with the onset of programmed cell death (PCD) at all stages of embryonic development, particularly in the head. Mutants contain extra cells in the head owing to decreased levels of cell death and show a pronounced defect in the morphogenetic movements of head involution (PubMed:7622034). Ectopic expression in the retina results in complete eye ablation (PubMed:7622034). Reduces levels of caspace-3 after exposure to ionizing radiation (PubMed:22964637). Simultaneous knockout of hid and Clbn/NEMF has a similar response to single mutants after exposure to ionizing radiation (PubMed:22964637). To D.melanogaster grim and rpr.