Basal and GATA-1–induced transactivation of P1 5′ deletion constructs.

(A) Schematic representation of GATA recognition sequences present infur P1 promoter fragments shortened in 5′ accordingly to endogenous SacI, NheI, or KpnI restriction sites. Base positions are numbered relative to the TATA box. (B) Dami cells were incubated overnight with 100 nM PMA and were cotransfected with fur P1, P1-SacI, P1-NheI, or P1-KpnI constructs and either pMGS control vector or pMGS–GATA-1 vector. Luciferase activity is expressed as fold-increase relative to the P1 promoter cotransfected with the pMGS control vector. Data are expressed as the mean ± SEM; n = 3. **P < .001, compared with promoter constructs without GATA-1.