Depleting conditioned medium of FL decreases the phosphorylation of FLT3 in EOL-1 cells. Conditioned medium of EOL-1 cells were first incubated with anti-FL monoclonal antibody followed by incubation with Protein G–agarose. The immunoprecipitates were then separated from the medium by centrifuging. Conditioned medium treated with an isotype control antibody was used as the control. EOL-1 cells were washed twice and cultured in the anti-FL– or isotype control antibody–treated conditioned medium for 1 and 3 hours. Total cellular protein was immunoprecipitated with anti-FLT3 antibody. The immunoprecipitates were resolved by 8% SDS-PAGE and subjected to immunoblot analysis with antiphosphotyrosine antibody 4G10 (top panel). The same blot was stripped and reprobed with anti-FLT3 antibody (bottom panel).