Mutation of SK-1 blocks the Ang-1 effects on permeability change. (A) HUVECs were infected with adenoviral carrying EV, SK-1, SK^G82D, or SK^S225A. After 48 hours, SK-1 activity was measured from cells that were either untreated (−) or treated with Ang-1 (+). Pooled data from 3 experiments are shown, expressed as the fold change in relation to EV untreated cells, normalized to 1.0 (*P < .01 versus untreated EV-infected cells or untreated SK-1-infected cells). NS indicates no significant difference versus untreated SK^G82D or untreated SK^S225A cells. (B) HUVECs were infected with EV, SK-1, SK^G82D, or SK^S225A in adenovirus. After 72 hours, cells were either untreated (−) or treated with Ang-1 (+) for 30 minutes and permeability measured. Permeability is given as the FITC-dextran passage in 30 minutes. Shown are the pooled data from 3 experiments (*P < .01 vs nontreated EV-infected cells). NS indicates no significant difference versus untreated SK-1, SK^G82D, or untreated SK^S225A-infected cells. All data are mean plus or minus SEM. (C) HUVECs were infected with SK-1 or SK^S225A in adenovirus. Forty-eight hours after infection, cells were lysed after either no treatment (−) or treatment with Ang-1 (+). Phospho-SK-1 is shown in the top and total SK-1 in the bottom panel.