Expression of Muc-1 core protein on MM patient and normal donor plasma cells. BM plasma cells from 2 representative MM patients (A) and 2 representative normal donors (B) are shown. Files were gated for CD38^hi45RA⁻ plasma cells (15% to 87% and 1% to 5% were present in MM patients and normal donors, respectively). Muc-1 on plasma cells was plotted as a histogram, with bold lines indicating staining with the VU-4H5 or VU-3C6 anti–Muc-1 MoAbs and the thin lines representing staining by an identically gated isotype-matched control MoAb.