Cell cycle analysis of Ba/F3 cells expressing ▵ABD EPO R/ABL. Cells were first synchronized in G1 by IL-3 deprivation for 16 hours (−EPO) and then cultured with 5 U/mL EPO for another 24 hours (+EPO). Cell cycle analysis was performed with propidium iodide staining, analyzing 10,000 cells/point by flow cytometry. In the experiment shown, the proportion of cells in G1, S, and G2/M were, respectively, 83%, 12%, and 5% (full length −EPO); 55%, 45%, and 1% (full length +EPO); 90%, 7%, and 4% (▵ABD −EPO); and 89%, 8%, and 3% (▵ABD +EPO).