A, B) Frequencies of chromosomal interchanges after 48 hr of continuous exposure to 0, 5 or 15 ng/ml MMC or 0, 50 or 100 ng/ml DEB. 1 At 100 ng/ml DEB excessive chromosomal damage was observed in one of the averaged experiments and the outcome was set to 100% chromosomal aberrations which is an underrepresentation of the actual damage level. +: complemented with FANCD2 or MLH1, -: mock complemented, error bars indicate standard error.