Cell cycle phase recovery from bleomycin-induced potentially lethal damage.

Mammalian cells treated during mitosis with the anticancer drug bleomycin cannot recover from potentially lethal damage. G1- and S-phase cells treated in a similar manner can recover. In synchronized G1- and S-phase cells, and in asynchronous and nondividing populations, the final survival values of recovered cells have always been found to be greater than 0.2. These data suggest that a certain fixed amount of recovery can occur, regardless of the degree of initial bleomycin-induced damage. The mechanism of this particular phenomenon is unknown.