Quantification of cell cycle-related gene expressions in tbx5 deficiency zebrafish embryos using a semi-quantitative PCR. A-D: The cell cycle regulatory genes p27 (A), p57 (B), bad (C) and bax (D), were significantly activated in tbx5-MO-treated embryos. (n = 3, 50 embryos/stage; relative expression, gene expression/b-actin expression). Data are presented as the mean ± S.D. An asterisk indicates a significant difference (p < 0.05).