FANCI missing the EDGE motif fails to correct MMC sensitivity in the FA-I F010191 fibroblasts. (A) F010191 fibroblasts were transfected with empty vector or the indicated FANCI expression constructs. Forty-eight hours after transfection, cells were treated with 2mM HU for 24 hours and processed for immunostaining. FANCD2 and BRCA1 nuclear foci formation was analyzed by immunofluorescence as previously described. (B) FANCD2 nuclear foci after HU treatment were quantified. Error bars represent SD from 3 independent experiments. (C) FA-I F010191 fibroblasts were transfected with either empty vector or the indicated FANCI expression constructs; and 48 hours after transfection, cells were treated with MMC at the indicated dose for 5 more days. Percentage cell survival is shown as an average of 3 independent experiments. Error bars represent the SD for the different experiments performed.