Together with the megakaryocytes, also monocytes play a key role in the overwhelming release of proinflammatory and profibrotic mediators (e.g., TGF-β, PDGF, bFGF and VEGF) that act on stromal cells and prompt the development of PMF-associated abnormalities of the BM architecture, such as BM fibrosis and osteosclerosis [6,7,33,34]. Here, FGF2 is linked to osteosclerosis.