Inhibitory effect of recombinant PEDF on HUVEC proliferation in vitro. The culture supernatants were collected from Ad-PEDF, Ad-null infected and NS treated B16-F10 cells. A 1:2 dilution series of each supernatant were further prepared and applied to HUVEC cells. The proliferation of HUVEC was measured with an MTT assay. The supernatant from Ad-PEDF infected cells inhibited the proliferation of HUVEC in a dose-dependent manner.