Viability of FL5.12 clones expressing Flag-Bcl-2 or Flag-Bcl-XL after treatment with S-phase specific chemotherapy drugs. (A) Cells were seeded at 1 × 105 cells/mL in triplicate wells in media containing IL-3 and increasing concentrations of methotrexate. Cells were lysed at 72 hours and analyzed by flow cytometry as described in Fig 2. A statistical significance was found between Flag-Bcl-2 and Flag-Bcl-XL clones at 0.1, 1, and 10 mg/mL of drug (P < .001, Student's t-test). (B) Cell viability was determined as above at each time point following continuous incubation in media containing IL-3 and 1.0 μg/mL of methotrexate. Cells were seeded at 1 × 105 cells/mL in triplicate wells and analyzed by flow cytometry as described in Fig 2. A statistical significance was found between Flag-Bcl-2 and Flag-Bcl-XL clones at Days 3 and 4 (P < .001, Student's t-test). (C) Cells were seeded at 1 × 105 cells/mL in triplicate wells in media containing IL-3 and increasing concentrations of fluorouracil. Cells were lysed at 72 hours and analyzed by flow cytometry as described in Fig 2. A statistical significance was found between Flag-Bcl-2 and Flag-Bcl-XL clones at each concentration of drug (P < .001, Student's t-test). (D) Cells were seeded at 1 × 105 cells/mL in triplicate wells in media containing IL-3 and increasing concentrations of hydroxyurea. Cells were lysed at 72 hours and analyzed by flow cytometry as described in Fig 2. A statistical significance was found between Flag-Bcl-2 and Flag-Bcl-XL clones at 10, 100, and 1,000 μg/mL of drug (P < .001, Student's t-test). Graphs shown in A, B, C, and D are the mean ± SD of triplicate cultures and representative of at least two separate experiments.
