SLC9A1 and cancer: It is well known that the Na+/Ca2+ exchanger type 1 (NCX1), which generally transports Ca2+ out in exchange for Na+ ions, operates predominantly in reverse or “retrograde” mode in cancer cells [46,47,48]; consequently, intracellular Ca2+ increases the promoting of the formation of a Ca2+-Calmodulin complex which regulates the functioning of NHE-1 [49].