WSS, but not PGE₂, contributes to survival and proliferation of cells in the AGM. (A) Representative plots of cell cycle analysis by BrdU incorporation and DNA content analysis. (B) Cellular proliferation is increased in ungated AGM cells cultured with WSS, as measured by total percentage of the population in S, G2, and M phases. No effects on cell cycle are detectable in the CD144⁺ CD45⁻ population (n = 3 independent experiments; two-tailed Student’s t test: WSS relative to static, *, P = 0.025). (C) Events collected from Annexin V binding assays are gated for analysis of cells that are live, undergoing early apoptosis, or are in late stages of apoptosis or necrosis. (D) Analysis of Annexin V staining in the ungated population indicates that 5 dyn/cm² WSS protects AGM cells from apoptotic cell death (n = 4 independent experiments; two-tailed Student’s t test: WSS relative to static, *, P = 0.049). Survival of CD144⁺ CD45⁻ endothelial cells is higher in the presence of WSS, and indomethacin has minimal effect on sheared cultures (WSS-indomethacin relative to static-indomethacin, two-tailed Student’s t test: *, P = 0.035). Treatment of static cultures with indomethacin produced moderate but insignificant elevation in nonviable CD144⁺ CD45⁻ cells (static relative to static-indomethacin, Student’s two-tailed t test: P > 0.05). Data are represented as mean ± SEM.