SLC9A1 and Barrett esophagus: Besides, it was found that NHE1 activity but not NHE1 expression was increased by acid pulse stimulation in ex vivo Barrett’s esophagus tissue, and that the elevated NHE1 activity may be responsible for the hyperproliferation of Barrett’s esophagus epithelial cells, probably mediated by PKC (Fitzgerald et al., 1998).