EKLF-GATA1 fusion proteins activated δ-, γ-, and β-globin promoter activity in K562 cells. ELKF, GATA1, fusion EKLF-GATA1 (EG) vector, or vector only was cotransfected with δ-, γ-, or β-globin promoter reporter constructs (A) or wild-type or mutant δ-globin promoter reporter constructs (B) into K562 cells. The level of promoter activity was evaluated 48 hours after transfection by measurement of firefly luciferase activity relative to the internal control renilla luciferase activity using the dual luciferase assay system essentially as described by the manufacturer. (A) Fold increase was calculated compared with expression in mock-transfected K562 cells. *P < .05 versus mock-transfected cells. (B) Fold increase was calculated relative to expression in mock-transfected cells. **P < .01 or ***P < .001 versus corresponding wild-type transfected cells. Error bars indicate SD of the mean of 3 independent experiments.