CXCL12 and essential thrombocythemia: It was previously reported that hematopoietic cells with JAK2 mutations secreted IL‐1β and induced the destruction of the bone marrow niche via the reduced expression of CXCL12.28 In contrast, bone marrow CXCL12‐positive cells were increased in MPN cases without ODM, especially in cases in which PV or ET transformed to secondary MF.