TEL-JAK2(5-19)Tyr314Phe does not alter constitutive activation of ERK1/2, p38, or SAPK/JNK.

(A) Ba/F3 and the indicated Ba/F3-TEL-JAK2 cell lines were depleted of cytokine and then stimulated in the presence (+) or absence (−) of IL-3. Phosphorylated ERK1 and ERK2 were detected by IB lysates with an antibody specific for phosphorylated ERK1/2 (pERK1/2) (upper panel). Total ERK1/2 was detected upon reprobing (lower panel). (B) The indicated cell lines were depleted of cytokine and then stimulated in the presence (+) or absence (−) of IL-3. Phosphorylated p38 was detected by IB lysates with a phosphorylation-specific p38 antibody (pp38) (upper panel). Total p38 was detected upon reprobing (lower panel). (C) The indicated cell lines were depleted of cytokine and then stimulated in the presence (+) or absence (−) of IL-3. SAPK was immunoprecipitated, and an in vitro kinase assay was performed using GST–c-Jun as substrate. Reaction mixtures were resolved by SDS-PAGE, and radiolabeled proteins were detected by PhosphorImager analysis (upper panel). Total SAPK was detected by IB with a SAPK antibody (lower panel).