Although the upregulation of BCR-ABL expression is similar in both WT and DKO B-cell progenitors (Fig. 2j, k), aPKCλΔ/Δ and DKO chimeric mice did not develop aggressive B- ALL, suggesting that aPKCλ is required for the development of BCR-ABL induced B-ALL. Here, ABL1 is linked to precursor B-cell acute lymphoblastic leukemia.