Morphology of cells expressing cytoplasmic truncations of the FIΔ activated mutant. (A) Control cells (expressing wt hβc) were cultured in the indicated growth factors for 5 days. Cells expressing truncations of the activated mutant were cultured in the absence of growth factor for 5 days. At day 5, cells were cytocentrifuged to assess morphology. Original magnification, × 400. (B) Differential counts from cytospins done at day 5. For each sample, 200 cells were scored microscopically for morphology. The combined data from a minimum of 3 independent experiments is shown. The standard error of the mean was less than 10% for all samples.