Asthma induces DNA damage responses, as indicated by immunoblotting results of 4 key DNA repair proteins. NU7441 markedly increased γH2AX and Rad51 levels, while Ku70 and PARP-1 levels were reduced. Immunoblotting images for γH2AX, Ku70, Rad51 and PARP1 were shown, β-actin was used as an internal control (A). Relative density analysis of Ku70 (B), γH2AX (C), Rad51 (D) and PARP-1 (E) were shown respectively. Bars indicate the mean density ratio ± SEM (n=4). *, OVA group vs. Normal group, P<0.001; #, NU7441 group vs. OVA + vehicle group, P<0.001. OVA, ovalbumin.