Lnk inhibits signaling pathways induced by MPLW515L. (A) BaF/MPL515 and UT7/MPL515 cells were treated with either 25 μM AG490 (JAK2 inhibitor), 16 μM LY294002 (PI3K inhibitor), 25 μM PD98059 (MAPK inhibitor), or dimethyl sulfoxide (DMSO) (inhibitor solvent). Proliferation was measured by cell counts. Data represent the mean (± SD) of duplicate samples and are representative of 2 independent experiments. (B) Transfected BaF/MPL515 and nontransfected BaF/MPLWT cells were depleted of cytokines for 4 hours and then stimulated with Tpo (1 ng/mL, 30 minutes). Protein lysates were analyzed by Western blot for the phosphorylated and total protein levels of Stat3, Erk, and Akt. Lysates from similarly treated cells were immunoprecipitated with JAK2 antibody and analyzed by Western blot with phospho-JAK2 and JAK2 antibodies.