To identify a specific marker on the surface of Ph+ leukemia cells for possible targeted therapy, whole-genome expression matrix (GSE5550) was applied to compare the differences of CD34+ cells in the bone marrow of untreated chronic myeloid leukemia (CML) patients and healthy volunteers in GEO database. The gene discussed is CD34; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.