CD34 and leukemia: In spite of the anticipated substantial inter-animal variability, this panel of miRNA reproducibly distinguished between cohorts (Fig. 4a): miR-155 was elevated in Molm-14- and CD34+-engrafted animals but not NSG controls, miR-150 separated Molm-14 from CD34+ engraftment, miR-221 was altered at late but not early leukemia time points, and miR-1246 increased over time in leukemia-, but not nonmalignant CD34+ cell-engrafted mice.