FACS analysis of tie expression on HUVECs treated with PMA. HUVECs in 100-mm dishes were left untreated (A), or treated with PMA for 30 minutes (B), 2 hours (C), or overnight (D). Cells were harvested with EDTA at 4°C and incubated with either control IgG (- - -) or anti-tie MoAb 42G10 () in PBS containing 1% BSA. FACS analysis was performed as described in Materials and Methods.