Presented a dramatic difference of immunohistochemistry assay in 4 groups. (A) Normal group; (B) OVA group; (C) NU7441 group; (D) OVA + vehicle group and (E) the percentage of γH2AX-positive cells with magnification of 40×. The frequency of γH2AX positive cells in (B) was significantly increased compared with (A). (D) had no effect on it, while (C) augmented frequency of γH2AX-positive cells. *, OVA group vs. Normal group, P<0.001; #, NU7441 group vs. Vehicle group, P<0.001. OVA, ovalbumin.