SU5416 and SU6668 inhibit c-kit tyrosine phosphorylation in MO7E cells.

Serum-starved MO7E cells were treated with the indicated concentrations of SU5416 (A) or isotype control E-cadherin antibody (D) for 2 hours, or SU6668 (B) or SU-A (C) for 48 hours, prior to stimulation with 250 ng/mL SCF for 15 minutes. SCF (100 ng/mL) was incubated with the SCF neutralizing antibody for 2 hours prior to addition to cells (D). Cells were harvested, lysed, and immunoprecipitated with an anti–c-kit antibody. After SDS-PAGE and transfer to nitrocellulose, the blots were probed with an anti-phosphotyrosine antibody (top) and subsequently stripped and reprobed with an anti–c-kit antibody (bottom).