Inhibition of GGTase I by GGTI-298 reduces cell viability and induces apoptosis. (A) Plasma cell lines RPMI 8226, L363, XG-1, and U266 were treated for 2 or 4 days with solvent control, different concentrations of the farnesyl transferase inhibitor FTI-277 (2.5, 5, 10, 15, 20, or 30 μM; ○), or different concentrations of the geranylgeranyl transferase I inhibitor GGTI-298 (2.5, 5, 10, 15, 20, or 30 μM; •). The percentage of viable cells, relative to the solvent control-treated cells, was measured by MTT assay. Experiments were performed 3 times in triplicate. Data are presented as mean ± SEM. (B) Plasma cell lines RPMI 8226, L363, XG-1, and U266 were treated for 2 or 4 days with solvent control (□), FTI-277 (20 μM; ▤), or with GGTI-298 (20 μM; ▪). The percentage of apoptotic cells was determined by annexin V assay. Shown is the sum of the percentages of early and late apoptotic cells. Experiments were performed 3 times in triplicate. Data are presented as mean ± SEM.