HDAC4 and cancer: HDAC4 and/or HDAC5 have been linked to tumorigenesis, tumor progression or chemoresistance in a variety of cancers, such as colon, urothelial, gastric, haematological, pancreatic, esophageal, or glioma [1,3,4,5,6,7,8,9,10,11,12,13].