B-1 progenitor acute lymphoid leukemia.

In this issue of Blood, Yin et al demonstrated that engineered BCL6 interacting corepressor protein (Bcor) mutation in hematopoietic stem/progenitor cells of sensitized mice induced acute lymphoid leukemia (ALL) of B-1 progenitor phenotype, which has been recently identified by them. The intriguing aspect of this report is the complete penetrance of B-1 progenitor leukemia by Bcor mutation, which selectively developed among other various progenitors in the bone marrow (BM).