Distinct granular expression of Ang-2 in endothelial cells. (A) RT-PCR analysis identifying Ang-2 expression in HUVECs, HAoECs, HSaVECs, HUAECs, and HDMVECs, but not in HUASMCs and the mammary and melanoma tumor cell lines R30C and A375 (TBP, control RT-PCR for the TATA box-binding protein). (B) RT-PCR analysis of endothelial cell and smooth muscle cell Ang-1 and Ang-2 production identified endothelial cells as a source of Ang-2 and smooth muscle cells a as source of Ang-1 (lanes 2 and 3 are Ang-1 RT-PCRs; lanes 4 and 5 are Ang-2 RT-PCRs). (C) Soluble Tie-2-Fc receptor bodies identify both Ang-1 and Ang-2. Tie-2-Fc stains permeabilized endothelial cells in a distinct granular manner and permeabilized smooth muscle cells with a uniform cytoplasmic pattern. (D) Retrovirally overexpressed Ang-2 is localized in endothelial cells in a characteristic granular pattern (arrows) and in smooth muscle cells with a uniform cytoplasmic distribution. In contrast, Ang-1 displays a uniform cytoplasmic distribution pattern in endothelial cells and smooth muscle cells. (E) Colocalization of endogenous and retrovirally overexpressed Ang-2. Nontransfected cells only express endogenous Ang-2 (arrows). Scale bar = 20 μm (C-E)