Characterization of 5TGM1 myeloma cells. (A) Hematoxylin and eosin (H&E) stained section of a lumbar vertebra from the 5TGM1 founder animal, showing myeloma cells (MY), which have almost completely replaced the normal bone marrow and are associated with osteolysis. Note that trabecular bone is absent from the growth plate shown at left and greatly reduced in the growth plate shown at right. Arrowheads indicate areas where cortical bone has been destroyed, allowing tumor cells to invade the surrounding tissue. This animal was paraplegic at the time of death and in this section, the spinal cord (SP) can be seen to be surrounded by myeloma cells, which has resulted in spinal compression (bar = 200 μm). (B) Giemsa stained cytocentrifuge preparation of cultured 5TGM1 myeloma cells, exhibiting a characteristic myeloma morphology (bar = 100 μm). (C) Coomassie blue-stained SDS-PAGE analysis of serum from control mice (lanes 1, 2), 5TGM1 myeloma-bearing mice (lanes 3, 4), and the 5TGM1 founder animal (lane 5), lane 6 shows 1 μg of IgG2b standard for comparison. The arrow indicates the IgG2b band. (D) Identical gel to C, which was analyzed by Western blotting using antibodies against mouse IgG2b. Lanes 1 through 6 are the same as for C.