Figure 2.

HR frequencies induced by TFO-directed psoralen ICLs on plasmids in HeLa cells. Plasmids containing 350 bp (A), 700 bp (B) or 1.4 kb (C) between supF copies were treated as described in the Materials and Methods section: white bars, plasmids with no treatment; gray bars, plasmids treated with UVA only; black bars, plasmids treated with the psoralen-conjugated TFO1 + UVA irradiation. Plasmids were isolated from HeLa cells 48 h after transfection and HR frequencies determined by blue-white screening of the colonies. All results shown are from at least three independent experiments (error bars represent the SDs), P-values were derived from one-way ANOVA.