(A) Cytokine-induced phosphorylation of STAT5. Control (lanes 1, 2, 9, and 10) and JAK3-deficient patients cells (lanes 3 through 6, 11, and 12) were stimulated with indicated cytokine for 15 minutes, lysed, and immunoprecipitated (IP) with STAT5A-specific antiserum (α-STAT5A). After transferring to a nylon membrane, complexes were immunoblotted (IB) with α-PY (top). The membrane was then stripped and reprobed with a-STAT5A (bottom). (B) Cytokine-induced phosphorylation of STAT6. Control (lanes 1 through 3) and JAK3-deficient patients cells (lanes 4 through 15) were left unstimulated or stimulated with IL-2 or IL-4, lysed, and immunoprecipitated (IP) with STAT6 antiserum (α-STAT6). After electro-transferring, immunocomplexes were immunoblotted (IB) with phosphotyrosine-specific monoclonal antibody (α-PY, top). The same membrane was then stripped and reprobed with α-STAT6 (bottom).