RPS6KB2 and myelodysplastic syndrome: To determine which BM cell subpopulation was responsible for establishing secondary transplants from primary mice with ENU-induced AML and MDS, we next FACS purified four BM cell subpopulations including the HSC-containing KLS positive and hematopoietic progenitor cell-containing KLS negative cells as well as the Lineage positive and Lineage negative/c-Kit negative (“c-Kit negative”) cell subpopulations (Figure A in S1 File).