Introduction of a FANCA cDNA reduces MMC sensitivity in UoC-M1. MMC resistance was evaluated in transduced UoCM-1 cells using cytogenetic analysis of radial formation after treatment with MMC. Transduction with a FANCA cDNA (UoC-M1/FA) reduced MMC resistance significantly (*P = .002). Neither FANCC nor FANCG transduction (UoC-M1/FC and UoC-M1/FG) significantly altered MMC sensitivity (P = .059 and P = .064, respectively). UoC-M1/FF demonstrated continued MMC sensitivity in 2 independent experiments with 38% and 26% radial formation in each (of 50 metaphases analyzed per experiment). Values shown are means ± SD.