Activation of JAK2 by wild-type and mutant GM-CSF receptors. Indicated 32Dcl3 cell lines were stimulated with diluent (D), 200 pmol/L mGM-CSF (M), or 400 pmol/L hGM-CSF (H), and lysed. Lysates were immunoprecipitated with anti-JAK2 antibody from Santa Cruz Biotechnology, Inc and normal goat serum (*) as a negative control. Immunoprecipitates were subjected to SDS-PAGE and transferred to Hybond-ECL filters. Filters were probed with 4G10 antiphosphotyrosine antibody, stripped, and reprobed with anti-JAK2 antibody.