The JAK-STAT6 signaling pathway is involved in the induction of LMP-1. (A) Immunoblot analysis of total cell extracts of the IL-4– or IL-13–treated (50 ng/mL, 30 minutes) KMH2, KMH2-EBV, and Jijoye M13 cells with antibodies specific for phospho-Tyr641 STAT6 (pY-STAT6) and total STAT6. The latter membrane was reprobed with β-actin–specific antibodies. (B) Expression of LMP-1, phospho-Tyr641 STAT6 (pY-STAT6), total STAT6, and β-actin in total cell lysates prepared from the KMH2-EBV cells treated with IL-4 or IL-13 (50 ng/mL) for 6 hours. The cytokine-treated cells were preincubated for 1 hour with 50 or 200μM AG490 or similar volume of ethanol as control. (C) Expression of LMP-1, total STAT6, total STAT3, and β-actin in total cell lysates of IL-4– or IL-13–treated KMH2-EBV cells. Two days before the addition of the cytokines the cells were transfected with STAT6-specific or control siRNA and cultured in complete medium without antibiotics. IL-4 (10 ng/mL) or IL-13 (50 ng/mL) was added for 24 hours before the lysates were prepared. (D) Expression of phospho-Tyr641 STAT6 (pY-STAT6), total STAT6, and β-actin in total cell lysates prepared from the L1236, L428, L540, HDLM2, KMH2, KMH2-EBV, KMH2(PM), and KMH2-EBV(PM) cells. (E) Immunoblot analysis with the use of LMP-1, EBNA-1, EBNA-2, and β-actin antibodies. KMH2-EBV or 3 different clones of KMH2-B958EGFP (cl.2, cl.3, cl.7) cells were treated with 50 ng/mL IL-4 for 24 hours, and total cell lysates were prepared. NS denotes a nonspecific protein detected by the anti–EBNA-1 antibody.