Morphology of cells expressing cytoplasmic tyrosine mutants of the V449E activated mutant. (A) Cells expressing the indicated cytoplasmic tyrosine substitutions were cultured in the absence of growth factor for 5 days and 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 are shown. The standard error of the mean was less than 10% for all samples.