Conditioned medium from CX3CL1-stimulated RPMI-8226 human multiple myeloma cell line induced the differentiation of osteoclasts from precursor cells, which implicates the CX3CL1-CX3CR1 axis in the progression of multiple myeloma through the generation of a niche supporting myeloma cells in the bone. Here, CX3CL1 is linked to plasma cell myeloma.