quantification of target mRNA was performed with semiquanti- tative RT-PCR. The primer sequences for the respective genes are shown in Table 1. The amplification for each mRNA was performed in the linear range for RT-PCR by optimizing the template concentration and limiting the amplification cycles to below 30 to ensure exponential amplification. Western blot analysis The cells were rinsed twice with ice-cold PBS and harvested by scraping in 80 ml RIPA buffer [50 mM Tris, pH 8.0, 150 mM NaCl, 1 mM EDTA, 1% (v/v) NP-40, 0.5% (w/v) NaDOC, 0.1% SDS, 1 mg/ml aprotinin, 1 mg/ml leupeptin, 1 mg/ml pepstatin, 2 mM PMSF, 2 mM NaF, 4 mM Na3VO4], followed by rocking at 4uC for 30 minutes. The cell lysates were then clarified by centrifugation at 12,000 g for 10 minutes. The proteins were quantified using DC protein assay (Bio-Rad, Hercules, CA). 60 mg proteins were resolved by SDS-PAGE and then electrophoretically transferred to PVDF membrane. 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