Synergism of 1-beta-D-arabinofuranosylcytosine with itself and aphidicolin.

JU56 cells have been exposed to 1-beta-D-arabinofuranosylcytosine (ara-C) in S phase, and again to aphidicolin (APC) or ara-C during G2, and examined for chromosomal aberrations at c-metaphase. It was found that the two exposures acted synergistically in the production of chromosomal lesions of both the chromatid and isochromatid type. The results were interpreted as indicating that inhibition of the G2 repair system prevented the repair of DNA single-strand regions produced by the incorporation of ara-C during semi-conservative DNA synthesis.