Effects of various KIT^WT (WT) mutants on the factor-dependent growth and receptor tyrosine phosphorylation of Ba/F^WT cells.

(A) Proliferation of Ba/F3 cells stably expressing various KIT^WT (WT) mutants at various concentrations of rmIL-3 or rmSCF was measured with the [³H]thymidine incorporation assay. Cells transfected with pEF-BOS vector alone (Vector) were used as a negative control. Three independent assays were performed with comparable results, and the data from a representative experiment are shown. Each point represents the mean of triplicate samples. Bars represent standard errors. At some data points, the standard error was too small to be shown by bars. (B) KIT was immunoprecipitated with ACK2 mAb from lysates of the indicated cells and was blotted with the indicated antibodies described in the legend to Figure 4. Similar results were obtained from 3 independent experiments. Y indicates tyrosine (Tyr); F, phenylalanine (Phe).