STAT5B and Airway obstruction: To assess whether the survival of circulating granulocytes, including those that extravasated into the lung, depended on the continuous expression of hyperactive Stat5, we treated MMTV-tTA TetO-Stat5 Stat5ΔN/ΔN mice with Dox after they developed high granulocyte counts and exhibited signs of airway obstruction.