MF inhibits the growth of tumor cell lines of the nervous system (A), breast (B), prostate (C), ovary (D), and bone (E). Cells were seeded at a density appropriate for each cell line, allowed to adhere for 24 h, and then exposed to the indicated concentrations of MF for 72 h. At the end of the experiment, cells were harvested by trypsinization and counted by microcytometry. Growth curves are expressed as the percent-growth of MF-treated cells with respect to vehicle-treated cell growth. The growth of vehicle-treated cells was calculated as the difference between the total number of cells at 0 h and 72 h of treatment, and was designated as 100% growth. Data points represent the mean ± s.e.m. of at least 3 independent experiments completed in triplicate.