Inhibition of programmed cell death by catalase and phenylalanine methyl ester.

1. Programmed cell death proceeds by an unknown mechanism which results in characteristic morphological changes known as apoptosis. 2. We have proposed that, in hormone-induced apoptosis, cell death may be the result of an attack of cells destined to die by cytotoxic macrophages. 3. We have investigated the effects of superoxide dismutase, catalase and the macrophage toxin, phenylalanine methyl ester, on the regression of tadpole tail slices in culture. 4. Our findings, that regression of bullfrog tadpole tails is blocked by catalase and phenylalanine methyl ester, support the working hypothesis.