"Appropriate clearance of apoptotic cell (cell corpse) is an important step of programmed cell death. Although genetic and biochemical studies have identified several genes that regulate the engulfment of cell corpse, how cell corpse is degraded after internalized in engulfing cell remains largely elusive. Here we show that vps-18, the C. elegans homologue of yeast Vps18p, is critical to cell corpse degradation. VPS-18 is expressed and functions in engulfing cells. Deletion of vps-18 leads to significant accumulation of cell corpses that are not degraded properly. Furthermore, vps-18 mutation causes strong defects in the biogenesis of early endosomes, late endosomes and lysosomes, thus affecting endosome-lysosome trafficking and lysosomal protein degradation. Importantly, we demonstrate that the internalized cell corpse is unable to fuse with the aberrant lysosomes in vps-18 mutants. Our findings thus provide direct evidence for the important role of endosomal/lysosomal degradation in proper clearance of apoptotic cells during programmed cell death."