The

Flk-1 promoter is activated by c-Ets1 and c-Ets2.A293 cells were cotransfected with LacZ (A,B) or luciferase (C) reporter gene constructs containing Flk-1 gene regulatory elements and with expression vectors for c-Ets1, c-Ets2, or pcDNA3 as control. The structures of the reporter gene constructs are shown in the bottom panels. (A) Cotransfection with a LacZ reporter gene construct containing the 939-bp Flk-1 promoter and the 430-bp minimal enhancer. (B) Cotransfection with a LacZ reporter gene construct containing the TK promoter and the 430-bp minimal enhancer. (C) Cotransfection with a luciferase reporter gene construct containing the 939-bp Flk-1 promoter. Relative promoter activities were determined as described in “Materials and methods.” The promoter activities of the control transfections were arbitrarily set at 1. The relative induction levels shown in A and C are not comparable because of the different stabilities of the different reporter gene products (β-galactosidase versus luciferase).