In addition, we found that the activation of NCX1 by extracellular high calcium microenvironment increased the osteoclastic activity, indicating that NCX1-induced calcium influx of myeloma cells activates JNK/c-Fos/NFATc1 pathway and modulates RANKL-induced osteoclast differentiation. This evidence concerns the gene TNFSF11 and plasma cell myeloma.