HOXB8 and leukemia: To overcome these limitations, we took advantage of the conditionally blocked in differentiation and cytokine-dependent mouse haematopoietic progenitor cell line Hoxb8-FL16 to model MLL-ENL-induced leukaemia, which mirrors the behaviour of classically derived MLL-ENL cell lines both in vitro and in vivo18,19, but in addition also shows a clear linear relationship between the parental and transformed states.