TEL-JAK2 expression results in constitutive phosphorylation of p38.

Ba/F3 and Ba/F3-TEL-JAK2 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 with a p38 antibody (lower panel). (B) A total of 2000 Ba/F3 cells (closed squares) and Ba/F3-TEL-JAK2(5-19) cells in the absence of IL-3 (open circles) or Ba/F3-TEL-JAK2(5-19) in the presence of IL-3 (closed circles) were seeded into 96-well plates containing media of increasing SB203580 concentration. The cells were incubated for 48 hours at 37°C prior to the addition of XTT and PMS. Absorbance was read at 450 nm following 4 hours of incubation at 37°C.