HUVEC were cultured with the indicated concentrations of JS-K. At the indicated time points cell growth was scored as outlined in the Methods section. JS-K treatment led to a dose-dependent inhibition of HUVEC growth. The IC50 at 24, 48, and 72 hours was 0.432, 0.466, and 0.505 µM, respectively. (Averages and SEM of 3 separate experiments).