HMECs express EP2 and EP4 receptors. HMECs were stimulated with bFGF (10 ng/mL), VEGF (10 ng/mL), or SDF-1α (100 ng/mL) for either 4 or 18 hours. Thereafter, cells were stained with antibodies to EP2 (cell surface staining) or EP4 (intracellular staining) receptors and analyzed by flow cytometry. Control antibody is depicted by filled histograms. EP2 and EP4 receptors are depicted by the empty histograms. The figure shows one representative experiment of 3 performed.