Both A1 and pim-1 are required to inhibit apoptosis and promote proliferation of the BCR/ABL-carrying cells.

(A) Apoptotic proteins. Parental cells and cell clones expressing BCR/ABL proteins, A1 protein, and/or pim-1 protein were starved from IL-3 for 6 and 12 hours and the expression of proteins regulating apoptosis was detected by Western analysis. Bad phosphorylated (upper band) and unphosphorylated (lower band) proteins are visualized. Results represent 2 experiments. (B) Cell cycle. The same cells were incubated without IL-3 for 0 or 24 hours. DNA content was determined by flow cytometry after staining with propidium iodide. Results are representative of 3 independent experiments.