RUNX2 and osteoporosis: In osteoporosis, there is a reduction in the acetylation of the H3K9/K14 and H4K12 regions in the regulatory regions of the RUNX2 and OSX genes, and an increase in acetylation at these same sites in the regulatory region of the PPARy2 gene in mesenchymal stem cells (MSCs) derived from bone marrow.