SK activates the PI-3K/Akt pathway but not the MAPK pathway. (A) Western blot of the phosphorylation of Akt (p-Akt) and total Akt (Akt) in ECs^SK and ECs^EV under basal conditions (HM) and in response to 6 hours of serum deprivation (SF). (B) The pooled data from 5 separate endothelial cell lines quantified for p-Akt compared with total Akt. *P less than .05 for ECs^SK (▪) compared with ECs^EV (□) in SF conditions. Bars represent SEM. (C) Phosphorylation of ERK1/2 (p-ERK1/2) and total ERK1/2 expression in cells taken from basal conditions (HM), after 6 hours of serum deprivation (SF), and in cells subjected to serum deprivation for 6 hours and then stimulated with 5 μM S1P for 10 minutes.