Inhibition of SDF-1α–induced activation and phosphorylation of PI3-kinase by pretreatment with the JAK2 inhibitor, AG490.

CTS cells, pretreated with AG490 (100 μM) (+) or DMSO (−) for 2 hours, were stimulated with 20 nM SDF-1α for 1 minute and then lysed. Total cell lysates were immunoprecipitated with PY20 antiphosphotyrosine antibody (pTyr). The immunoprecipitates were analyzed by Western blotting with anti-p85 antibody (A). Total cell lysates were immunoprecipitated with PY20 antiphosphotyrosine antibody (pTyr) (B) or anti-p85 antibody (C). PI3-kinase activity was measured by a PI3-kinase assay, as described in “Materials and methods.” PIP indicates phosphatidylinositol 3-phosphate.