JAK2 and leukemia: Recently, evidence has suggested that Klf4 may serve as a tumor suppressor in leukemia.23,24 Previous studies have demonstrated that Klf4 is repressed by CDX2 in AML and colon cancer,25 and downregulation of Klf4 by Jak2 allows for increased proliferation of progenitor cells.26 However, the exact role of Klf4 and HDACs in leukemia, particularly in AML, is unclear.