KLF4 and plasma cell myeloma: Elevated levels of stem cell markers were observed in some myeloma B cell subsets, namely Nanog (in hscs and pre-pro-B cells, immature B cells, and unswitched and switched memory B cells), KLF-4 (in hscs and pre-pro-B cells, and from immature B cells to switched memory B cells), Oct3/4 (in B cell precursors pre-pro-B and pre-BI/II cells), and Sox2 (in naive B cells and switched memory B cells).