SIPA1 and chronic myelogenous leukemia, BCR-ABL1 positive: To investigate the effects of the Sipa1-deficient host environment on the CML-inducing activity of the primary Bcr-Abl+ HPCs, we first transferred the primary lineage marker negative (Lin−) BM cells from Wt B6 mice retrovirally transduced with p210Bcr-Abl into Wt and Sipa1−/− B6 mice intravenously at 1.5 × 104 cells/mouse according to the standard BM transplantation (BMT) procedure34.