Increased Tie2 signaling in sprout endothelial cells of Pdpn^−/− and Clec-2^−/− diencephalon. (A-B) Confocal images of diencephalon radial sprouts with an antibody to phospho-TIE-2 (Y991), a marker for TIE-2 activation (A), or antibody probe to phospho-SRC (Y418), a marker for SRC activation (B). Bar graphs represent the quantified ratio of sprout phospho-TIE-2 intensity (A) or phospho-SRC intensity compared with the paired WT (B). Dashed outlines show each sprout. (C-D) Confocal microscopy of junctional VE-cadherin expression in radial sprouts of diencephalon at E11.5 costained with anti-CD31, an endothelial cell junction marker (C), or with anti-ERG, a marker for endothelial cell nuclei (D). Bar graph on right represents the quantified ratio of sprout VE-cadherin intensity compared with paired WT (C). Data represent mean ± standard error of the mean; n, number of embryos. At least 3 sprouts/embryo analyzed. Scale bars, 20 μm. *P < .05; **P < .01.