Transactivation of the MBP P2 promoter by GATA-1 and GATA-2 (A) and competitive inhibition by GATA-2 (B). Transactivation of the MBP P2 promoter (bp −117/MBP-pXP2) in Jurkat cells, in which neither GATA-1 nor GATA-2 transcription factors are expressed. The T-lymphocytic Jurkat cell line was transfected by the electroporation method with 15 μg of the MBP P2 promoter construct −117 MBP-luc along with one of the following expression constructs: pXP2-MBP (control), 20 μg of pEF-BOS (the control plasmid containing elongation factor promoter without cDNAs); pXP2-MBP + GATA-1, 10 μg of pEF-hGATA-1 and 10 μg of EF-BOS; pXP2-MBP + GATA-2, 10 μg of pEF-hGATA-2 and 10 μg of pEF-BOS; pXP2-MBP + GATA-1 + GATA-2, 10 μg of pEF-hGATA-1 and 10 μg of pEF-hGATA-2. Luciferase activity was measured 24 hours after transfection and normalized for transfection efficiency based on the activity of a cotransfected β-galactosidase expression vector (CMV-βGAL). Data are shown as the mean of three independent experiments (±SEM).