Quantitative mRNA expression of Dppa2, Dppa3, Dppa4, and HDAC1 genes in TS cells (ICRTS1, BDF1TS1, BDF1TS2, BCF1TS1, and BCF1TS2) and ES cells (TT2). The relative amounts of transcripts for Dppa2, Dppa3, Dppa4, and HDAC1 genes are expressed relative to GAPDH values. Data were normalized to TT2 ES cell levels. The expression level of each line indicates the mean±standard error of the mean (SEM) of three trials. Bars with different letters above them differ significantly (p<0.05).