hGATA-specific mRNA expression. (A) GATA-binding site in the Epo 5′ promoter region (shaded region). (B) Northern blot analysis of Hep3B cells. Northern blot analysis was performed using 20 μg total RNA from control Hep3B cells (lanes 1 and 2), Hep3B cells treated with 50 μmol/L CoCl₂ for 24 hours (lanes 3 and 4), and Hep3B cells treated with 1% O₂ for 24 hours (lanes 5 and 6). UT7 cells (lanes 7 and 8) were used as a positive control for hGATA-1 and 2. The filter was hybridized to a probe of hGATA-1, -2, and -3 cDNA and then stripped and rehybridized to a β-actin cDNA probe. (C) Northern blot analysis of HepG₂ cells. Northern blot analysis was performed using 20 μg total RNA from control HepG₂ cells (lanes 1 and 2), HepG₂ cells treated with 50 μmol/L CoCl₂ for 24 hours (lanes 3 and 4), and HepG₂ cells treated with 1% O₂ for 24 hours (lanes 5 and 6). The filter was hybridized to a probe of hGATA-1, -2, and -3 cDNA, respectively, and then stripped and rehybridized to a β-actin cDNA probe.