Previous evidences have suggested that Klf4, which is a zinc finger transcription factor, can function as both a tumor-suppressor gene and an oncogene and might be specifically targeted by certain HDACs.15, 16, 17, 18, 19, 20 Consistent with our study, Klf4 has been recently shown to act as a tumor suppressor in Hodgkin lymphoma,23,28 but the exact mechanism by which Klf4 affects myeloid leukemia remains unclear. The gene discussed is KLF4; the disease is myeloid leukemia.