Abstract
Protease inhibitors suppress radiation transformation in vitro. A 24 h treatment with the protease inhibitor antipain at 5 days post-irradiation was sufficient to significantly suppress radiation transformation. Comparable experiments performed with cycloheximide, an inhibitor of protein synthesis, showed that this metabolic inhibitor could suppress radiation transformation when present immediately following the X-ray exposure but not when present for 1 day at 5 days post-irradiation. Antipain is suppressing an ongoing cellular process occurring in response to X-irradiation.