Cell cycle progression of murine sarcoma cells after x irradiation or heat shock.

DNA histograms of exponentially growing EMT-6 cells in vitro were obtained at regular time intervals after exposure at 300 rads of x rays or one hour of heat shock at 43 degrees C. After either treatment, about 70% of the cells retained clonogenicity. Irradiation induced the expected block in the G2 + M phase, resulting in an increase of cells in that phase during the first 5 hours after exposure. Heat shock caused a block in both the S and G2 +M phases.