FIG. 4.

Jak1 activation versus mutations and deletions of the intracellular domain of IL-7R. Transfected D1 cells were maintained in mIL-7, washed, and stimulated with 50 ng of hIL-4/ml for 15 min. Total Triton X-100 cell lysates were resolved by sodium dodecyl sulfate-PAGE, and Western blotting was performed with an antibody against phospho-Jak1 or Jak1. The activation of Jak1 required Box1 but not Y449.