FIG. 2.

IR increases cellular levels of PCNA. Confluent cultures of CREF cells were released from growth arrest by replating at 70% confluence. Six hours after replating, the cells were mock irradiated or exposed to 12 Gys of γ radiation. Cell lysates were prepared in radioimmunoprecipitation assay buffer from the unirradiated and irradiated cells, and equal amounts of protein from each lysate were assessed for PCNA levels by immunoblotting. Top and bottom panels show immunoblots indicating PCNA levels in irradiated and unirradiated CREF cells, respectively, at the indicated times postexposure.