SLC9A1 and melanoma: Concurrent application of bafilomycin A1, the specific V-Type ATPase inhibitor during the sodium-free pHi recovery phase achieved near-complete inhibition of pHi recovery in A375 cells (Fig. 3e,f), suggesting that V-Type ATPase and NHE1 were synergistic in mediating recovery from intracellular acidity in the A375 melanoma cells.