Fig. 6.
Orthovanadate activates JNK-1 and p38.
(A) HCD57 cells were deprived of EPO and cultured 24 hours in 0 (lanes i and ii), 10 μmol/L (lanes iii and iv) or 70 μmol/L orthovanadate (lanes v and vi). The cells were either stimulated with 10 units EPO per milliliter (lanes ii, iv, and vi) or mock treated for 5 minutes (lanes i, iii, and v). JNK-1 was immunoprecipitated from the cell extracts; activity was determined by the phosphorylation of GST-Jun in an in vitro kinase assay. (B) HCD57 cells were deprived of EPO and cultured 24 hours in 0 (lanes i and ii), 10 μmol/L (lanes iii and iv) or 70 μmol/L orthovanadate (lanes v and vi). The cells were either stimulated with 10 units EPO per milliliter (lanes ii, iv, and vi) or mock treated for 5 minutes (lanes i, iii, and v). Whole cell extracts were analyzed by Western blot with anti–phospho-p38 antibody. The blot was stripped and reprobed with anti-p38 (lower panel) antibody.