Uropods act as attachment sites in contacts between myeloma cells and other cell types.

ARP-1 cells were seeded on a confluent layer of cells from the human osteosarcoma cell line HOS. After attachment of the myeloma cells, the coculture was stained with FITC–anti-syndecan-1 and studied with a confocal laser microscope. A stack of 60 pictures in the x-y plane was taken. The distance between adjacent pictures was 0.5 μm. Upper 3 pictures show 2 myeloma cells in the x-y plane with the picture number from the top of the stack indicated. The picture in level 50 also shows some staining of the adherently growing osteosarcoma cells. Lower panel is a z-section of the myeloma cells, showing uropods attaching to the osteoblast-like cells, which are faintly visible in the lower quarter of the picture.