Using GAB2 knock-out mice [6], we analyzed the in vivo role of GAB2 in a chronic-phase CML mouse model in which a tetracycline (tet) regulated BCR::ABL1 transgene is expressed in hematopoietic stem cells in their native microenvironment [10, 14]. The gene discussed is BCR; the disease is chronic myelogenous leukemia, BCR-ABL1 positive.