Sustained activation of ▵716 cells in response to G-CSF.

Ba/F3 cells were transfected with the WT (A, C) or Δ716 G-CSFR (B, D). In (A) and (B), cells were serum- and cytokine-deprived and then stimulated with 100 ng/mL G-CSF for the indicated times. In (C) and (D), cells continuously growing in G-CSF–containing media were subsequently transferred to media devoid of all cytokines and analyzed at the indicated times. Whole-cell lysates were immunoblotted with the 4G10 anti-phosphotyrosine antibody. Arrows indicate proteins with prolonged tyrosine phosphorylation in Δ716 cells.