SLC4A4 and glioblastoma: We also show that following induction of chemical hypoxia, NBC activity is differentially regulated in the transcriptionally distinct glioblastoma cells: hypoxia significantly upregulated NBCe1 protein abundance, but not protein levels of NBCe2 and NBCn1 and enhanced NBCe1 transport in MES-like hypoxia-dependent cells, but not in hypoxia-independent or AC-like cells (Figure 2, Figure 3 and Figure 4).