Growth properties of M1 and M1E2F-1 cells untreated and treated with IL-6.
(A) Growth kinetics of M1 and M1E2F-1 cells treated with IL-6. Cells were seeded at 0.15 × 106/mL in the presence or absence of IL-6 (50 ng/mL) and the number of viable cells was determined at the indicated times by trypan blue dye exclusion and counting in a hemocytometer. On day 3 untreated M1 and M1E2F-1 cells and IL-6–treated M1E2F-1 cells were diluted and reseeded at 0.15 × 106/mL. Each time point is the average of at least 3 experiments, with a standard deviation of up to 15%. Four other independent M1E2F-1 clones gave similar results and M1-puromycin control clones behaved indistinguishably from parental M1 cells. (B) Flow cytometric analysis (FACS) of IL-6–treated M1 and M1E2F-1 cells. FACS analysis was carried out as described in “Materials and methods.” Note the lack of a sub-G0/G1 peak in the IL-6–treated M1E2F-1 sample, indicating an absence of apoptotic cells.
