Enhanced transcription of p53-inducible genes and DNA damage in RNase H2B–deficient cells. (A) Comparison of gene expression profiles in liver cells from Rnaseh2b^KOF/KOF and WT control E14.5 embryos (n = 3 both groups) by microarray analysis. The graph shows genes with more than twofold difference in transcript levels between the groups. (B) Validation of mRNA levels in E14.5 fetal liver by qRT-PCR for the Rnaseh2b and three p53-inducible genes. Results of three pairwise comparisons of Rnaseh2b^KOF/KOF and WT control samples are displayed. (C and D) Rnaseh2b^KOF/KOF (n = 6, white bars) or control (WT/WT or KOF/WT, n = 11, black bars) E18.5 thymocytes (C) and Rnaseh2b^KOF/KOF (n = 4, white bars) or control (WT/WT or KOF/WT, n = 9, black bars) E18.5 liver cells (D) were immunostained for phosphorylated histone H2AX (γ-H2AX). 400 nuclei per individual thymus or liver were evaluated in a blinded fashion. Error bars indicate ±SD in all graphs.