Effect of o-vanadate and Syk inhibitors on phosphorylation of band 3 in intact human erythrocytes. Proteins were separated by 8% SDS-PAGE, after which band 3 phosphorylation was analyzed by Western blotting using an anti-phosphotyrosine (anti-pTyr) antibody. Erythrocytes were treated for 1 hour with different concentrations of o-vanadate (o-v; A) and for different incubation times (B) with 2mM o-vanadate in the absence (panel A lanes 1-5; panel B lanes 1-4) or presence (panel A lanes 6-10; panel B lanes 5-8) of Syk inhibitors II and IV (Syk I). Images were acquired using a laser infrared fluorescence detector (Odyssey; LI-COR Biosciences).