Schema for competitive engraftment RM transplantation experiments. A mobilized, autologous peripheral blood CD34⁺ cell apheresis product was split into 2 equal halves. Each half was transduced using a different marker (GFP or YFP). After 10 Gy of myeloablative total-body irradiation (TBI), gene-marked grafts were then delivered at the same time, either using the OIB technique or IV via a central line. Engrafted progeny were identified from the 2 different transplant methods to compare their relative contribution to hematopoiesis by using peripheral blood samples gated on granulocytes and analyzed for GFP and YPF by flow cytometry.