MiR-125a extends clonal lifespan, while serial transplantation ‘activates’ dormant clones (A) Serial transplantations of control LT-HSC or (B) miR-125a overexpressing LT-HSC. Barcoded bone marrow cells were isolated from multiple skeletal regions of primary recipients, and serially transplanted (origin of cells depicted over mouse pictogram). Clonal make-up in secondary (and tertiary) mice was compared with clonal make-up of the primary recipient that served as bone marrow donor. The color code indicates which clones were originating from which mouse. Size of the clone is indicated by the size of the circle (to estimate the relative contribution to granulocytes, the barcode representation in granulocytes was divided by total barcode representation (granulocytes+ Ter-119+ T cells+ B cells). Many clones that were detected in the peripheral blood of secondary recipients were also present in the blood of the primary recipient (detected in 1° PB). However, some secondary clones were only present in the bone marrow of the primary recipient (indicated by ‘not detected in 1° PB′). Only clones that contributed at least 0.5% to Gr-1+ at week 16 are shown for the primary recipient).