Expression of TEL-Jak2 fusion proteins in Ba/F3 cells. Ba/F3 (lanes 1 and 6), Ba/F3-HA-TEL-Jak2 JH1 subclone 36 (lane 2), Ba/F3-HA-TEL-Jak2 JH2+JH1 subclone 23 (lane 3), Ba/F3-HA-TEL-KI-Jak2 JH1 subclone 11 (lane 4), and Ba/F3-HA-TEL-Jak2 JH2 subclone 4 (lane 5) were metabolically labeled with³⁵S-cys/³⁵S-met. Immunoprecipitations were conducted with Jak2 antibodies that recognized the Jak2 JH1 domain (pan Jak, lanes 1 through 4) or Jak2 JH2 domain (Jak2, lanes 5 and 6). Immunoreactive species were analyzed via PhosphorImager detection.