The product of the reaper (rpr) gene is required for programmed cell death in Drosophila. We examined rpr expression during ectopic cell deaths caused by ionizing radiation or aberrant development. In both instances, dramatic induction of rpr expression was observed. A genomic fragment upstream of rpr confers this regulatory behavior upon a lacZ reporter transgene. In a model cell culture system, conditional expression of REAPER is sufficient to induce massive apoptosis that can be prevented by the anti-apoptotic protein p35. Overall, these results suggest that diverse signals converge at, or upstream of, rpr-associated transcriptional regulatory elements that can function to initiate a common apoptotic pathway involving ICE-like protease activity.