The Ets site E#3 is required for the activity of the

Flk-1 promoter in transgenic mouse embryos. (A) An embryo transgenic for a construct containing the 939-bpFlk-1 promoter and the 430-bp minimal enhancer, showing a uniform and strong vascular LacZ expression. (B,C) LacZ expression in mouse embryos transgenic for constructs containing the 939-bpFlk-1 promoter with a mutation in either the Ets site E#3 (B) or in the Ets site E#6 (C), and the 430-bp minimal enhancer.