The invention provides molecular markers that are associated with the progression of chronic myeloid leukemia (CML), and methods and computer systems for monitoring the progression of CML in a patient based on measurements of these molecular markers. The present invention also provides CML target genes, and methods and compositions for treating CML patients by modulating the expression or activity of these CML target genes and/or their encoded proteins. The invention also provides genes that are associated with resistance to imatinib mesylate (Gleevec™) treatment in CML patients, and methods and compositions for determining the responsiveness of a CML patient to imatinib mesylate treatment based on measurements of these genes and/or their encoded proteins. The invention also provides methods and compositions for enhancing the effect of Gleevec™ by modulating the expression or activity of these genes and/or their encoded proteins.