IFNα-induced Janus kinases activation HUT78 cells. The cells were treated with (+) or without (−) IFNα (10,000 U/mL for 5 minutes) and whole cell extracts were prepared for immunoprecipitation with anti-Tyk2 (Fig 5A) or anti-Jak1 (Fig 5B) antibody. The immunocomplex was then analyzed by Western blot using anti-phosphotyrosine (anti-pY) antibody (upper panels). The same blot was stripped and reprobed with anti-Tyk2 or Jak1 antibody to determine the levels of protein in each lane (lower panels).