Figure 6. DNA damage assessments and DNA damage repair gene expression during the first wave of hepatocyte proliferation after partial hepatectomy (PH) in Keap1+/+ and Keap1+/− mice. (A) Immunohistochemistry was performed using the γ-H2A.X antibody with liver sections prepared from regenerating livers at the indicated time points after PH. DyLight 488-conjugated AffiniPure Goat Anti-Mouse IgG was used as a secondary antibody. γ-H2A.X⁺ foci in hepatocyte nuclei exhibit green fluorescence. Representative nuclei with 4 or more γ-H2A.X⁺ foci are indicated by arrows. (B) The nuclei with more than 4 γ-H2A.X⁺ foci were counted in 5 randomly chosen microscope fields (200x) per section. The data are shown as the means per field ± SD (n = 3 mice/time point/genotype). Asterisks represent P < 0.05 in comparison between Keap1+/+ and Keap1+/− mice. (C) Total RNA was prepared from liver tissues collected prior to or after PH at the indicated time points. Hepatic mRNA levels of RAD51 and RAD51l1 were quantified by qRT-PCR and are expressed as the mean fold changes compared with wild-type normal controls ± SD (n = 3 mice per time point per genotype). Asterisks represent P < 0.05 in comparison between Keap1+/+ and Keap1+/− mice.