Hematopoietic niches: a new therapeutic target for PMF? New therapeutic strategies must target HSCs, and JAK-STAT is a legitimate target pathway as demonstrated by recent results with JAK2 inhibitors. However, they must also target the different cellular and/or acellular components of hematopoietic niches to manipulate the balance of competition between endosteal and vascular niches and therefore to modify the stem cell outcome. Actually, therapeutic strategies such as anti–TGF-β, anti-VEGF or inhibitors of their receptors, bone remodeling drugs, fibrosis and metalloprotease (MMP) inhibitors are in progress in PMF.