HGF promotes proliferation of MSCs. MSCs were treated for 1 or 2 days as indicated before ³H-thymidine was added to the media. The amount of incorporated ³H-thymdine was measured after another 18 hours of culturing. Bars represent mean + SEM of triplicate wells. Control levels of ³H-thymidine incorporation per well were 3866 counts/min on day 1 and 2969 counts/min on day 2. The concentrations of cytokines were 300 ng/mL BMP-2 and 100 ng/mL HGF.