To examine maturation of myeloma B lymphoid lineage, we first evaluated B cell precursors/progenitors from CD34+, CD38lo, and CD45lo hscs to pre-pro-B (CD34+, CD38het, and CD45lo), pro-B (CD34lo, CD38+, and CD45lo), pre-BI (CD34het, CD10+, and CD19lo), and pre-BII (CD34–, CD10lo, CD19lo, and IgMlo) cells. Here, MME is linked to plasma cell myeloma.