The cytotoxic effects of ARC towards cells are similar to that of sangivamycin and toyocamycin. A) Time course analysis of ARC on 14C-leucine viability of HL60 cells (upper panel) and MCF7 cells (lower panel). Data from at least 2 replicate experiments each with triplicate points were pooled and the SEM are shown when they are greater than the symbol. B) Time course analysis of ARC on a panel of 12 cell lines representative of 6 different tumor types. C) Comparison of the cytotoxic effects of ARC over 6 days with those of fludarabine (Flud), toyocamycin (TOY), sangivamycin (SAN) and thioguanine (TG) towards HL60 (upper panel) and MCF7 (lower panel) cells. The IC50 defined as the concentration of drug required to inhibit 14C-leucine viability by 50% relative to control treated cells determined from at least two pooled experiments is plotted versus time. D) Comparison of activity of ARC with sangivamycin and toyocamycin over a panel of cell lines reveals a high correlation coefficient between ARC and sangivamcin. In all panels, cells were incubated with varying concentrations (0.1 – 1000 μM) of the indicated drug.