RUNX2 and plasma cell myeloma: By extracting CCM and applying it to both osteoclasts and osteoblasts, we found that RUNX2 upregulation in myeloma cells not only enhanced the promoting effect of myeloma cells on osteoclast activity but also the suppressive effect of myeloma cells on osteoblast activity and facilitated the differentiation of osteoclasts mediated by osteoblasts, ultimately aggravating bone destruction.