Specificity of antiphospho-STAT6 antibody for phospho-STAT6.

Antiphospho-STAT6 antibody was preincubated for 1 hour without peptide (A), with phospho-STAT6 peptide against which the antibody was raised (B), phospho-STAT3 peptide (C), or phospho-STAT5 peptide (D), prior to immunohistochemical staining of a case of classical HL. HRS cells demonstrate positive staining with antibody alone (A), which is completely abrogated by preincubation with the phospho-STAT6 peptide (B). Preincubation of antiphospho-STAT6 antibody with phospho-STAT3 (C) or phospho-STAT5 (D) peptides did not affect staining. Original magnifications, × 1340.