Fig. 3.

PCNA ubiquitination in RPA or ATR knockdown cells. (A) MRC5V1 cells were transfected with RPA70 siRNA. After a 72-h incubation, cells were either irradiated or not with 10 J m⁻² UV and incubated for 0.5 or 6 h. Cell extracts were analyzed by immunoblotting with (Top to Bottom) anti-RPA70, anti-Chk1-P-Ser-317, PC10, and anti-vimentin (loading control) antibody. Lanes 1, 3, and 5, nontargeting siRNA control. Lanes 2, 4, and 6, RPA siRNA-transfected samples. (B) MRC5V1 cells were transfected with nontargeting or ATR siRNA, UV-irradiated (20 J m⁻²) 72 h later, incubated for 6 h, and analyzed as in A. (C) Normal or Seckel syndrome lymphoblastoid cells were UV-irradiated with the indicated doses and incubated for 6 h before lysis and analysis.