In this study we show that a triple mutant of BCR-ABL with mutations of the direct binding sites for GRB2, CBL, p62DOK and CRKL, is defective for transformation of primary hematopoietic cells in vitro and in a murine CML model, while it retains the capacity to induce IL-3 independence in 32D cells. This evidence concerns the gene GRB2 and chronic myelogenous leukemia, BCR-ABL1 positive.