Morphologically, the BM of 1° and 2° 36S and STIF recipients demonstrated dense infiltration with cells showing myelomonocytic and monoblastic differentiation (Fig. 5d), resembling AML M4/M5, which is commonly associated with MLL translocations and overexpression of HOXA9 and MEIS1 in patients41,42. Here, HOXA9 is linked to acute myeloid leukemia.