In order to follow leukemia/lymphoma development kinetically and to gain insight into how different blood cell populations were affected by MYC and MYC/BCL-XL expression, hematopoietic development was studied in detail at 7, 14 and 35 days after transplantation of Mock/MYC- or MYC/BCL-XL-transduced HSC into recipient mice. This evidence concerns the gene MYC and leukemia.