The locus of action of 1-beta-d-arabinofuranosylcytosine in the cell cycle.

Abstract

Summary By taking advantage of the fact that 1-β-d-arabinofuranosylcytosine is metabolized slowly by asynchronous Don-C cells in culture, the locus of action of this drug was demonstrated to be the S-phase of the mitotic cycle, though the possibility of drug effect late in G 1 could not be entirely ruled out. Cells in G 1 , M, and G 2 at the time of drug exposure continued their march through the cycle until they encountered this sensitive phase and were killed. Survival of a small number of cells after one or two generations is probably related to a population of cells (5%) which do not label after continuous exposure to tritiated thymidine.