Bone marrow Lepr+ MSCs transdifferentiate into myofibroblasts in myelofibrosis in response to platelet derived growth factor receptor (PDGFR) stimulation, downregulating their production of hematopoietic niche support factors in parallel with their increased expression of fibrogenic and osteogenic genes (12, 21). Here, PDGFRB is linked to myelofibrosis.