Neutrophilic differentiation of 32D.C10 transfectants in response to G-CSF. (A) Morphology of 32D.C10 transfectants maintained in IL-3–containing medium (IL-3) or cultured for 8 to 11 days (WT, Y704F, Y729F, and Y744F) or for 3 days (Y764F) in the presence of G-CSF (May-Grünwald-Giemsa staining; original magnification × 630). (B) The percentages of terminally differentiated 32D.C10 transfectants cultured in G-CSF–containing medium. At least 200 cells were scored at the indicated times. (□) WT; (•) Y704F; (▵) Y729F; (▴) Y744F; (○) Y764F. (C) Net amount of mature neutrophils derived from 1 × 10⁵ 32D/WT and 32D/Y764F cells cultured in G-CSF–containing medium for 8 or 3 days, respectively. Data from five independent clones are shown.