CXCL12 and myelofibrosis: In primary myelofibrosis, CD9 is involved in the altered interactions between megakaryocytes and bone marrow mesenchymal stromal cells and participates in alterations affecting the survival, differentiation, and stromal cell-derived factor CXCL12 (SDF-1) with the CXC chemokine receptor 4 (CXCR4)-mediated migration of megakaryocytes, contributing to the occurrence of dysmegakaryopoiesis [22].