First strand cDNA was synthesized using reverse transcriptase (RT) and 1 μg of total RNA. Reactions were conducted in 20 μL of buffer containing; 0.5 μL oligo (dT)12-18 primer (Gibco/BRL, Grand Island, NY, USA), 50 mM Tris-HCl (pH 8.3), 75 mM KCl, 3 mM MgCl2, 40 mM DTT, 0.5 mM deoxynucleotide triphosphate (dNTP) mixture (Invitrogen, Carlsbad, CA, USA), 10 unit RNase inhibitor (Gibco/BRL), and 200 units of MMLV reverse transcriptase (Invitrogen). After incubation at 37°C for 60 min, reactions were stopped by heating at 70°C for 15 min. To remove remaining RNA, 1 μL of E. coli RNase H (4 mg/mL) was added to reaction mixtures and incubated at 37°C for 30 min. cDNAs obtained were used as a template for PCR amplification using gene-specific primers for target genes and for glyceraldehyde 3-phosphate dehydrogenase (GAPDH). Primer sequences are listed in Table 1 . 