Cells were suspended for cell sorting in Hanks’ balanced salt solution (HBSS) containing 5%(vol/vol) fetal bovine serum (FBS) and 2 mM EDTA as previously described27 . The following antibodies were used to define lineage positive cells: 145-2C11 (CD3ε), GK1.5 (CD4), 53–6.7 (CD8), RB6-8C5 (Ly-6G/Gr1), M1/70 (CD11b/Mac-1), TER119 (Ly-76/TER119), 6B2 (CD45R/B220), and eBio1D3 (CD19). Red blood cells were lysed with RBC Lysis Buffer (eBioscience) before staining for lineage markers. For the Lin− Sca-1+ cKit+ (LSK) bone marrow cell sorting, the antibodies 2B8 (cKit/CD117) and D7 (Sca-1/Ly-6A/E) antibodies were also used. To determine donor-derived chimerism in the transplantation-based assays, peripheral blood from the recipients was obtained by the submandibular bleeding method and prepared for analysis as previously described20 (link). All antibodies were purchased from eBioscience. Apoptosis assays were performed by staining cells with Annexin V and 7-AAD (BioLegend). Cell cycle status was analyzed by staining cells with 2.5 μg/ml PI containing 0.1% BSA and 2 μg/ml RNase after fixation with 70% ethanol. Flow cytometric analysis and cell sorting were carried out on the Moflo XDP, Cyan ADP (Beckman Coulter) or S3 (Bio-Rad), and the data were analyzed with FlowJo software (Tree Star Inc.).