B-myeloid conversion is through dedifferentiation. Representative flow contour diagrams of donor MZPs on day 4.5 (A) and day 9 (B) after cell transfer. Most donor CD45.2⁺ cells (upper left) converted to myeloid marker–negative or Lin⁻ cells, but by day 9, a small yet clearly discernable number of donor B cells had undergone dedifferentiation to an immature Lin⁻ cell type (lower left) exhibiting HSPC immunophenotype cKit⁺Sca1⁺Lin⁻ (lower right; n = 4).