Crkl immunoprecipitates from thrombopoietin (100 ng/mL for 1 minute) -treated platelets of CML patients contain a tyrosine-phosphorylated 95- to 100-kD protein that is also recognized by an anti-STAT5 MoAb. The same methods as in Fig 1 were used, except that platelets from CML patients were analyzed. Results are representative of three experiments from three different donors. (−) Resting CML platelets; (+) thrombopoietin-treated CML platelets.