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. 2004 Aug 15;18(16):1958–1963. doi: 10.1101/gad.1196104

Figure 1.

Figure 1.

ATR is required for damage-inducible monoubiquitination of FANCD2. (A) ATR siRNA A strongly inhibits MMC-induced monoubiquitination of FANCD2 in HeLa and U2OS cells. Silencing of FANCA suppresses FANCD2 monoubiquitination either with or without exposure to MMC. (B) Silencing of ATR with siRNA in U2OS cells suppresses FANCD2 monoubiquitination following exposure to HU, MMC, or IR for the indicated times. Suppression of ATR activity is demonstrated by decreased phosphorylation of Chk1 on S345 in response to silencing. (C) Silencing of ATM does not decrease FANCD2 monoubiquitination. (D) Flow cytometric analysis demonstrates that inhibition of damage-induced monoubiquitination of FANCD2 by suppression of ATR is not due to an alteration of cell-cycle progression. Histograms of DNA content are displayed, with S-phase index measured by BrdU incorporation as described (Andreassen et al. 2001), inset in each histogram.