MWCL-1 cell line morphology. (A) Hematoxylin and eosin staining demonstrating the heterogeneity of the WM tumor clone represented in MWCL-1 cells, including B lymphocytes, lymphoplasmacytic cells, and mature plasma cells (original magnification ×200, Olympic Provus AX70 microscope). (B) Immunofluorescence showing the presence of κ-light chain on the extracellular surface of MWCL-1 cells and cytoplasmic IgM.