Analysis of Runx1 functional domains involved in the Flk-1 promoter repression. (A) Schematic illustration of the structures of full-length Runx1 (αB1), its deletion derivatives, and K83E mutants. K83E mutant has an A>G substitution in exon 3 resulting in a missense mutation. (B) Effects of Runx1 and its mutants on Flk-1 promoter activity in BAECs. Results shown are representative of 3 independent experiments. RD indicates runt domain.