CBX4 and osteoarthritis: reported that CBX4 counteracts senescence in human mesenchymal stem cells (HMSC) by maintaining nucleolar homeostasis, and that CBX4 maintained nucleolar homeostasis by recruiting nucleolar protein-fibrillin and heterochromatin KRAB associated protein 1 (KAP1) within nucleolar rDNA, thereby limiting rRNA overexpression and attenuating the development of osteoarthritis in mice (36).