Generation of HUVECs overexpressing murine Ang-1 using a retroviral vector. (A) Expression of murine Ang-1 and human Ang-2 mRNA levels in HUVECs transduced with control retroviruses (MSCV) and retroviruses expressing murine Ang-1 (MSCV-Ang-1). **P < .01 compared with MSCV cells. (B) Immunoblotting of MSCV and MSCV-Ang-1 cell lysates for Tie-2, tyrosine phosphorylated Tie-2 (p-Tie-2), V5 tag, and Tie-1 proteins. Vertical lines indicate that lanes were not directly adjacent to each other in the original blots. (C) Detection of Ang-1 protein in the medium and extracellular matrix (ECM) of MSCV and MSCV-Ang-1 cell using immunoblotting. (D) Erk1/2 phosphorylation measured after 15 minutes' exposure to conditioned medium of MSCV and MSCV-Ang-1 cells. HUVECs were cultured in complete medium overnight and were then serum starved for 6 hours. The medium was then removed and replaced by conditioned medium collected from serum-starved MSCV and MSCV-Ang-1 cells. (E) Detection of IL-8 protein in the medium of MSCV and MSCV-Ang-1 cells using ELISA (n = 6). *P < .05 compared with MSCV cells. (F,G) Means (± SEM; n = 6) of cell number, BrdU incorporation and cleaved caspase-3 intensity after 2 days' culturing in culture medium containing 2% FBS. *P < .05 compared with MSCV cells.