Overexpression of Bcl-2 oncoprotein rescues the proliferation of TF-1 cells in IL-5. (A) Overexpression of Bcl-2 protein in TF/Bcl-2 cells. Two hundred and fifty micrograms of protein lysates from each indicated cell line were analyzed by Western blot for the expression of Bcl-2, Bax, and -tubulin proteins (indicated at the right-hand side of the figure). (B) The growth curves of TF/Bcl-2 cells in the indicated culture media. TF/Bcl-2 cells were grown in media as indicated and the viable cell numbers were determined at each time point by trypan blue staining. (C) TF/Bcl-2 and TF8 cells were refractory to SCF stimulation in IL-5–containing medium. TF-1, TF8, and TF/Bcl-2 cells were treated with IL-5 alone (□), SCF alone (▨), or IL-5 + SCF (▪) and the numbers of viable cells were determined by trypan blue staining at different time points. The dose of cytokines was the same as described in Fig 1. The results were the averages from three duplicated experiments. The error bars represent the standard deviations.