HDAC4 and acute lymphoblastic leukemia: Higher expression levels of some histone deacetylases (HDACs) have been detected in chALL including HDAC2, HDAC3, HDAC8, HDAC6, and HDAC7. Overexpression of HDAC1 and HDAC4 have been shown in T-ALL, while HDAC5 has higher expression in B-lineage ALL.