Ang-1 induces SK-1 activation in HUVECs through ERK1/2. (A) HUVECs were infected with adenovirus carrying hSK-1-FLAG. Cells were lysed after no treatment (Nil), treatment with Ang-1 at 0.2 μg/mL for 30 minutes (Ang-1), or pretreatment with U0126 (2 μM for 20 minutes) followed by treatment with Ang-1 (U0126 + Ang-1). Phospho-SK-1 in the top panel and total SK-1 in the bottom panel are shown. (B) HUVECs were untreated (−), or treated with Ang-1 for various times. Phospho-ERK is shown in the top panel and total ERK in the bottom panel. (C) HUVECs were untreated (Nil), treated with Ang-1 at 0.2 μg/mL for 15 minutes (Ang-1), or pretreated with U0126 (2 μM) for 20 minutes and then treated with Ang-1 for 15 minutes (UO126 + Ang-1). The SK-1 activity was measured. Pooled data from 3 experiments are expressed as in Figure 1A (mean ± SEM; *P < .05 vs untreated cells).