DKK1 and Miyoshi myopathy: In MM, tumor PCs produce both activators of OCs and inhibitors of OBs (80): MM cells increase the differentiation and activity of OCs by dramatically increasing the release of osteoclastogenic factors (81–87) and favoring the recruitment of OCs precursors (88–90), conversely, malignant plasma cells can elevate Dickkopf-1 (DKK1) levels (91) and decrease the essential OB transcription factor RUNX2 activity (92) leading to the suppression of osteoblast activity and osteoblast differentiation.