SU11657 inhibits TEL/PDGFβR kinase activity. (A) SU11657 inhibits TEL/PDGFβR tyrosine autophosphorylation. TEL-PDGFRB-transfected 32D cells were incubated in the presence of SU11657 or vehicle for 1 hour and protein lysates were harvested. TEL/PDGFβR was present in α-PDGFβR immunoprecipitates from TEL-PDGFRB-transfected 32D, but not untransfected control 32D cell protein lysates (left lane). Immunoprecipitates were immunoblotted using an antiphosphotyrosine antibody to determine the phosphorylation status of TEL-PDGFβR in SU11657- and vehicle-treated cells. (B) SU11657 inhibits TEL-PDGFRB-mediated factor-independent cell growth; 105 cells/mL TELPDGFRB-transfected 32D cells were grown in 0.1% SU11657 or vehicle (DMSO). Cells were plated in RPMI supplemented with 10% fetal bovine serum (FBS) and penicillin/streptomycin in the presence or absence of 1 ng/mL IL-3. Viable cells were detected via trypan blue exclusion and counted at 24-hour intervals. Experiments were performed in triplicate. Mean cell counts and SDs are shown.
