LPA and S1P promote growth of hES-NEP cells. (A, C) hES-NEP cells were plated in 24-well plates and grown to 50% confluence, and the treated with vehicle or 1–100 nM LPA (A) or S1P (C) for 36 hours and then counted. (B, D) Cells were incubated with vehicle or 100 nM LPA (B) or 100 nM S1P (D) and cell growth was determined at 12, 24, and 36 hours. Viable cells were counted and reported as the number of new cells/well. The number of cells at time zero (108,000) has been subtracted from all data shown. Data are representative of two independent experiments analyzed using an unpaired 2-tailed t-test. *: p < 0.05; **: p < 0.01.