HES1 forms MMC-induced foci. Localization of endogenous HES1 in HeLa, PD430T (FA-A), and PD430T complemented with the FANCA gene. Cells were double stained with anti-HES1 and anti-FANCD2 antibodies at 0 (A: untreated) or 4 (B) hours following treatment with MMC (50 ng/mL) and processed for immunofluorescence. Nuclei were labeled with TOPRO-3.