FIG. 4.

FANCD2(T691A,S717A) fails to upregulate its monoubiquitination after MMC cross-linker damage. FA-D2 fibroblasts were stably transduced with the cDNAs encoding wild-type (wt) or mutant FANCD2 proteins. Cells were treated with MMC, as indicated, and whole-cell extracts were immunoblotted with anti-FANCD2 antiserum. The upper band is monoubiquitinated FANCD2 (FANCD2-L), and the lower band is unubiquitinated FANCD2 (FANCD2-S). The ratio of FANCD2-L to FANCD2-S (L/S) was calculated by densitometry.