Figure 1.

SNM1B functions epistatically to FANCD2 in cellular survival to ICL damage. (A) FANCD2-deficient PD20F fibroblasts and PD20F cells complemented with FANCD2 cDNA (WT) were transfected with NS and siSNM1B-1. At 48 h post-transfection, cells were plated and treated with indicated MMC concentrations for 1 h. Percent survival compared with untreated samples was determined. Average of at least three independent transfections with standard deviation is shown. (B) FANCD2 monoubiquitination in NS- and siSNM1B-1-transfected cells. HeLa cells transfected with NS or siSNM1B-1 were treated with MMC (1 µg/ml) for 8 h at 48 h post-transfection. Cells were collected and the soluble and chromatin-associated proteins were fractionated. Western blots were probed with α-FANCD2 antibodies. Tubulin and γ-H2AX were used as controls for S1 and P2 fractions, respectively. The L/S ratios of FANCD2 are shown below blot and represent the average of three independent experiments. S1, soluble; S2, chromatin bound; P2, chromatin bound (tightly).