SLC9C1 and glioma: However, their poor recovery during this assay suggests that NHE activity is low in F98 glioma cells, in agreement with the study by Glunde et al., 2002 [51], who showed that extracellular acidification inhibits the activity of NHE-1 exchanger (sodium–hydrogen exchanger isoform-1) in glioma cell lines (C6 and F98).