(A) Schematic of experimental procedure. Absolute numbers of mouse (B) proerythroblasts (AML 1.8×105 ± 1.7 × 104 vs CB 2.5×105 ± 2.0×104; p=0.034), (C) normoblasts (AML 5.4×105 ± 6.4×104 vs CB 2.6×106 ±4.3×105; p<0.0001), (D) late normoblasts (AML 1.86×105 ±1.3×104 vs CB 1.9×106 ± 1.6×105; p<0.0001), and (E) reticulocytes (AML 2.0×105 ± 1.6×104 vs CB 8.6×105 ± 2.6×105; p=0.0007) in the BM of NSGspln--PDX (engrafted with SU540 (n=6) and SU575 (n=5)) compared to NSGspln--CB-CD34+ mice (n=4). Absolute numbers represent total numbers per mouse. Pearson’s correlation between absolute numbers of (F) proerythroblasts, (G) normoblasts, (H) late normoblasts, (I) reticulocytes and human AML BM engraftment. All R2 = Pearson correlation determination.