Taken into account that the SFK members Hck and Lyn are typically expressed in myeloid cells and are constitutively activated by the p210 isoform of BCR-ABL, it is tempting to speculate that activated SFK contribute to the persistent cytoplasmic localization of pSTAT5A observed in primary CD34+ CML cells [13,17,19,45]. This evidence concerns the gene ABL1 and chronic myelogenous leukemia, BCR-ABL1 positive.