Moreover, Komura et al. demonstrated that in FKBP51-overexpresssing cell line, STAT5 was sustainably activated in association with JAK2 phosphorylation implying the importance of this mechanism for spontaneous growth of megakaryocytes in idiopathic myelofibrosis In addition, in 2005, Komura et al. also showed that FKBP51 overexpression in UT-7/mpl cell line induced a sustained activation for the nuclear factor κB (NF-κB) after cytokine deprivation and this activation of NF-κB was also detected in proliferating megakaryocytes and in circulating CD34 + patient cells [48]. Here, FKBP4 is linked to primary myelofibrosis.