It has been previously described that the bone marrow from Gata1low mice expresses pro-inflammatory cytokines (TGF-β1), growth factors (osteocalcin, platelet-derived growth factor [PDGF], and vascular endothelial growth factor [VEGF]), bone morphogenic proteins (BMP-2, -4, and -6 and their receptors BMPR-IA and -II), and bone-specific matrix proteins (osteonectin, bone sialoprotein, and osteopontin), some of which are produced by malignant MKs, known to induce osteosclerosis at levels greater than normal, already at 1 month of age [25,30,31]. This evidence concerns the gene SPARC and osteosclerosis.