STAT5 phosphorylation after IL-5 stimulation is not blocked by Tat-dn-H-Ras.

Human blood eosinophils were incubated with 100 nM of Tat-dn-H-Ras or Tat-GFP for 30 minutes and then stimulated for 15 minutes with 300 pM IL-5. Resultant cell lysates were resolved by SDS-PAGE and processed for immunoblot analysis using either anti–phospho-STAT5 antibodies (A) or anti-active MAPK antibodies (B). The same experiment performed in panel A was performed with excessive concentrations of Tat-dn-H-Ras (C). An equal mass of protein in each sample was confirmed by immunoblotting with anti-STAT5 antibody (not shown). Data of 3 independent experiments are represented.