Ruxolitinib abrogates IL7-induced STAT5 phosphorylation. (A) ETP-ALL xenograft samples were treated for 30 minutes with vehicle (shaded) or 500 nM ruxolitinib (unshaded), and pSTAT5 levels were assessed by flow cytometry. (B) ETP-ALL xenograft samples treated as in A were subsequently exposed to vehicle or 100 ng/mL IL7 for 20 minutes, and pSTAT levels were measured.