Keywords: سایت ضعیف; HSPC; hematopoietic stem and progenitor cells; APH; aphidicolin; PBS; phosphate-buffered saline; DEN; diethylnitrosamine; BCR; breakpoint cluster region; LM-PCR; ligation-mediated PCR; CBFB; Fragile site; Hematopoietic stem cells; Leukemia; MLL; Topoisome