Figure 2.

Correlation between the XPA level and DNA excision repair activity in human cells. (A) Protein levels in NHF-1 cells transfected with different amounts of siRNA targeting XPA for 24 h were analyzed by immunoblotting with the indicated antibodies. CPB, cyclophilin B. (B and C) Residual (6–4)PP (B) or CPD (C) damage in genomic DNA was detected by immunoslot blotting using damage specific monoclonal antibodies. (D and E) Average repair values and standard deviations are shown for data from three independent experiments for the (6–4)PP (D) and CPD (E). (F and G) Initial repair rate for (6–4)PP (F) and CPD (G) were measured as a function of XPA protein level which was manipulated by knockdown of XPA using siRNA. The initial rates were calculated from the linear range of the kinetic data in D and E.