p300 and CBP mRNA expression levels during mouse heart development. RT-PCR data show that p300 (A) and CBP (C) mRNA expressions can be detected at various embryonic stages as well as in postnatal and adult stages. M represents DNA marker. (B, D) The line graphs summarize p300 (B) and CBP (D) relative expression levels corresponding to panel A and C, respectively. Data are expressed as a ratio of p300 or CBP mRNA to β-actin mRNA concentrations. Results are averaged from three independent experiments in each stage.