Quantitative RT-PCR analysis of imprinted gene expression.

The expression profiles of paternal and maternal imprinted genes were analyzed by real-time RT-PCR. All data are normalized to ACTB expression and calibrated on the ESCs, whose gene expression was considered 1 for all genes. Error bars represent mean values ± SEM of three independent experiments. Student’s t-test: ***, p<0.001; **, p<0.01; *, p<0.05.