Moreover, since the pH balance is maintained thanks to the activity of proton transporter proteins, also called proton pumps—such as carbonic anhydrases (CAs), Na+/H+ exchanger (NHE-1), and vacuolar-ATPase (V-ATPase)—selective targeting of these proteins has been explored as a novel anticancer strategy to alter the acidity of the tumor microenvironment. The gene discussed is SLC9A1; the disease is neoplasm.