By means of the ectopic expression of BRCA1 we show the involvement of BRCA1 in centrosomal aberrations observed in CD34+ cells soon after their transduction with BCR/ABL RVs, supporting the hypothesis that this phenotype constitutes an early event in the transformation of CML cells. This evidence concerns the gene CD34 and chronic myelogenous leukemia, BCR-ABL1 positive.