To test whether BM-MSCs are instructed to develop a myofibrotic phenotype by mutated MPN hematopoietic cells, we performed coculture experiments of peripheral blood-derived mononuclear cells (PB-MNCs) isolated from MPN patients with the JAK2 V617F mutation with BM-MSCs isolated from healthy donors. This evidence concerns the gene JAK2 and myeloproliferative disorder.