TST and ulcerative colitis: In addition, dysregulation of thiosulfate sulfurtransferase (TST) located on the luminal mucosal surface of normal colon results in ineffective detoxification of H2S, and expression of TST is lost in ulcerative colitis and advanced colon cancer, and reactivated by histone deactylase inhibitors [75], indicating that TST may be a factor for the cell loss and inflammation that accompany ulcerative colitis and ultimately CRC.