Taken together our observations of i) the inverse correlation between HES5 and HES6 in cancer cells treated with 5-aza-2′-deoxycytidine, ii) their inverse correlation in tumour-normal comparisons and iii) strong consensus HES5 binding sites at the HES6 gene locus suggests that HES5 may repress HES6 in prostate epithelial cells. The gene discussed is HES5; the disease is neoplasm.