FIG. 1.

SF/HGF prevents contact inhibition in U373MG cells. U373MG cells plated in medium containing 10% FBS at high density (HD) or low density (LD) were treated for 24 h with 100 ng of SF/HGF per ml. Fluorescence-activated cell sorter analysis (A and B) demonstrated that SF/HGF reduced the fraction of cells in G₁/G₀ by 29.6% (n = 3 experiments, SE = 4.3%) compared to untreated controls when cells were grown at high density. SF/HGF had no effect on cell cycle distribution in cells grown at low density. (C) MTT assay demonstrated SF/HGF increased U373MG cell number by 64.3% (n = 8 per group, P < 0.001, t test) when cells were grown for 72 h at high density. SF/HGF produced little mitogenic effect on cells at low density. (D) Growth curves comparing U373 cells engineered to secrete human SF/HGF (U373-SF) with control transfected SF-negative U373 cells (U373-Neo).