While, as anticipated by reports published by Liang et al. [32] that indicate reduced homing in an aged microenvironment, the frequency of GFP+ cells in PB was lower in aged recipients transplanted with control cells compared to young recipients, animals receiving the AML-ETO+ graft presented with the lowest chimerism in PB. The gene discussed is RUNX1T1; the disease is acute myeloid leukemia.