STI 571 does not inhibit granulocyte-macrophage colony-stimulating factor (GM-CSF)–dependent activation of MAP kinase.

Serum was withheld from M-07e cells overnight. The cells were then pretreated with various concentrations of STI 571 for 90 minutes before the addition of vehicle or GM-CSF (final concentration, 200 U/mL) for 15 minutes. Whole cell lysates were immunoblotted with an antibody specific for phospho-MAP kinase. The membrane was stripped and reprobed with an antibody for total p44 and p42 MAP kinase. The arrows indicate the locations of p44 and p42 MAP kinase. Representative results from 1 of 2 independent experiments are shown.