Cell survival studies and LC50 determination. Survival of drug-sensitive KB-3-1 and Pgp- expressing KB-8-5 cells grown in the presence of chemotherapeutic agent, colchicine (25μM; positive control), increasing amount of metallodrug 5 (2A, top), and gallium(III) nitrate (2B, bottom). Data for the gallium(III) nitrate is replotted for comparison from reference [41]. Cells grown in the presence of vehicle alone served as control preparations; data for cell survival in the presence of metallodrug 5 or gallium(III) nitrate was plotted as a percent of vehicle control. LC50 (μM): 5, KB-3-1, 1.93; KB-8-5, >100. Each point represents the mean value of triplicate determinations; bars represent ± SEM when larger than symbol.