AG-490 inhibits tyrosine phosphorylation of Janus tyrosine kinase 3 (JAK3) and signal transducer and activator of transcription 6 (STAT6).

(A) D10 cells were treated with DMSO (lanes a and b) or 100 μmol/L AG-490 (lanes c and d) for 16 hours and then stimulated with or without 100 nmol/L IL-4 at 37°C for 10 minutes. Cells were lysed, immunoprecipitated with anti-JAK3 (α-J3; upper panel) or anti-STAT6 (α-STAT6; lower panel), subjected to Western blotting with α-PY (antiphosphotyrosine), and then reprobed with anti-JAK3 or anti-STAT6 (indicated beneath phosphorylation blots) to verify equivalent loading. Arrow indicates migrational location of either JAK3 or STAT6. (B) Tyrosine phosphorylated proteins were normalized against total protein. The ratio of phosphorylated protein to unphosphorylated protein is plotted on the abscissa (arbitrary units) against AG-490 treatment (ordinate).