Ablation of KLF2 and KLF4 leads to cranial hemorrhaging by E9.5. Light micrographs of E9.5 mouse embryo whole mounts were taken at 16X magnification. A) WT (n = 4); B) KLF2-/- (n = 3); C) KLF4-/- (n = 3); D) KLF2+/-KLF4-/- (n = 3); E) KLF2-/-KLF4+/- (n = 4) embryos are grossly normal. F) KLF2-/-KLF4-/- (n = 3) embryos show hemorrhaging and/or enlarged blood vessels in the head region. Arrowhead indicates hemorrhaging.