Effects of 26 chemicals that inhibit the FA pathway on HR efficiency, IR-induced foci formation of FANCD2, RAD51 and BRCA1, and IR-induced FANCD2 monoubiquitination. (See Additional file 4: Figures S2, Additional file 6: Figure S4, and Additional file 3: Figure S5 for details) Color-coded representation of HR efficiency in DR-GFP assay, the proportion of cells with IR-induced foci of the indicated proteins, and the proportion of FANCD2 monoubiquitinated form on Western blot (8 hours after 10 Gy), compared to untreated controls. U2OS-DR-GFP cells were used for all the experiments. An asterisk (*) indicates significant decrease compared to controls (p ≤0.05, paired t test, n = 3 to 7) in DR-GFP and foci formation experiments. N.D. = not determined.