Expression of differentiation markers and Mct8 mRNA in F9 cells. A–D, induction of markers of endoderm differentiation in F9 cells. Cells were grown in DMEM supplemented with 10% FBS and treated with or without tRA (1 μm) and/or 8-bromo-cAMP (1 mm) for 96 h, and quantitative RT-PCR of the indicated genes was performed. Quantification of those genes as well as the internal control Gapdh was obtained from standard curves of serial dilution series of cDNA mixture of tRA-treated cells and tRA/cAMP-treated cells. The sample quantification was then normalized to Gapdh. E–H, induction of neural differentiation markers in F9 cells. Cells were treated with or without tRA (1 μm) and 8-bromo-cAMP (1 mm) in DMEM/F-12 (50:50) with 2% FBS for 2 days or 7 days, and quantitative RT-PCR of the indicated gene was performed. Quantification was obtained from standard curves of serial dilution series of cDNA at day 2 and normalized to Gapdh. Values are expressed as means ± S.D. (n = 3). *, p < 0.01, when compared with untreated cells (day 0). Col4a1, collagen type IV α-1; Afp, α-fetoprotein, Lama1, laminin α1; Thbd, thromobomodulin; Mct8, monocarboxylate transporter 8; Snca, synuclein α; Otx1, orthodenticle homeobox 1; Nes, nestin; NeuroD1, neurogenic differentiation 1.