B-cell depletion in the BM of Apc^Min/+ mice. To identify B-cell maturation stages, cells were double-stained with monoclonal antibodies anti-B220 and anti-IgM. For analysis, a lymphoid FCS/SSC gate was set up to exclude other cell lineages and the B-cell maturation stages were identified as pro- and pre-B cells with a B220⁺/IgM^- phenotype, immature B cells with a B220⁺⁺/IgM⁺ phenotype, and mature B cells with a B220⁺⁺⁺/IgM⁺ phenotype. The proportions of cells present in each subpopulation are given as a percentage of the total B220-positive population. Results are representative of at least 3 different animals per group.