We have previously identified NME2 (Nm23-H2) as a tumor antigen in a patient with chronic myeloid leukemia (CML). Here we investigated the association between NME2 and Bcr-Abl. NME2 protein was highly overexpressed in the cytoplasm of peripheral blood mononuclear cells from 29/30 patients with CML at diagnosis and 10/10 patients resistant to imatinib. Protein was overexpressed in the absence of increased levels of mRNA and was limited to Bcr-Abl + populations, being absent from Bcr-Abl - patient cells, normal donors and 14/15 acute myeloid leukemia (AML) samples. Furthermore, the Bcr-Abl dependent overexpression of NME2 protein was reversed specifically by tyrosine kinase inhibitor (TKI) treatment of Ba/F3 expressing wild-type and TKI-sensitive, but not TKI-resistant, mutants of Bcr-Abl. The post-transcriptional up-regulation of the tumor antigen NME2 is therefore a common and specific property of CML closely associated with Bcr-Abl activity.