Cell cycle–dependent regulation of FANCC expression.

293 FANCC E2 cells were synchronized with hydroxyurea for 24 hours and then washed twice and cultured in complete growth medium. Cells were fixed and permeabilized at different time points after release (0 hours, 4 hours, 6 hours, 8 hours, 10 hours, and 12 hours). An asynchronous population of 293 FANCC E2 cells (Asynch.) and 293 Neo cells were also analyzed (Control). Cells were treated with nocodazole for 24 hours to induce M-phase arrest. (A) IFA of cells using monoclonal anti-FANCC antibody. No FANCC staining is detectable in 293 Neo (control cells). FANCC expression is lowest in cells at the time of or immediately after release from hydroxyurea synchronization. Highest FANCC expression is seen in cells 10 to 12 hours after HU release or in cells arrested in the M-phase by nocodazole. (B) Cell cycle distribution of cells shown in panel A. (C) Summary statistics. 200 cells in each condition were scored as negative or positive for FANCC expression. Bars depict mean ± SEM.