MPN MK-released factors affecting bone homeostasis. MK-released factors that enhance OB and/or OC development are depicted. Although not shown here, as noted in the text, depending on concentration, some factors can both enhance or inhibit the development of the same lineage, as in the case of the effect of TNF-α on OBs or TGF-β and IL-6 on OCs. Other factors have only a negative effect on function, such as the influence of IL-1β on OBs. Professional illustration by Patrick Lane, ScEYEnce Studios.