In order to test whether the generation of fibronectin by leukemia cells influences leukemia progression and accelerates BCR-ABL1+ CML similar to BCR-ABL1T315I+ CML, we transduced the BM of fibronectin flox/flox × Mx1-Cre (FN Mx1-Cre) mice with BCR-ABL1 or BCR-ABL1T315I, before transplantation into wildtype recipients and subsequent administration of poly I:C to induce Cre (Fig. S5C). Here, BCR is linked to leukemia.