SLC9A1 and neoplasm: Our data indicate that the ECM composition actively drives (i) the resting pHi in normal cells, the Panc1 tumor cells and their derived CSCs, (ii) the pHi response of these cells to the presence of NaHCO3 in both neutral and acidic pHe, (iii) their pHi recovery from an intracellular acid load, and (iv) their NHE1 activity.