Proliferation assay of BCR-ABL ΔP1,P2 mutant in 32D cells. 32D, 32Dp210, and 32Dp210ΔP1,P2 cells growing in the presence of IL-3 were washed three times with RPMI 1640 medium and plated at 1 × 10⁵ cells/mL in regular growth media with or without exogenous growth factor. Each day, viable cells were counted as assessed by exclusion of trypan blue. The data presented are representative of four separate experiments. Similar results were obtained in MTT assays. (▪), 32D + IL-3; (□), 32D − IL-3; (•), 32Dp210 + IL-3; (○), 32Dp210 − IL-3; (▴), 32Dp210(ΔP1,P2) + IL-3; (▵), 32Dp210(ΔP1,P2) − IL-3.