RTF is the a2 isoform of V0 subunit, which is one of the vacuolar H+-ATPase (V-ATPase) proton pumps and participates in the control of pH in normal and tumor cells via proton pumping across the membrane to the extracellular space or intracellular organelles, which, in turn, contributes to extracellular acidification and maintenance of relatively neutral cytosolic pH15. The gene discussed is ATP6V0A2; the disease is neoplasm.