There are two glutaminase isoforms that are encoded by different genes in human cells: the liver-type glutaminase, also known as LGA or GLS2 and the kidney-type glutaminase which is known as KGA or GLS1. 4 An upregulation of glutaminase C (GAC), a splice variant of GLS1, has been demonstrated in cancer cells in comparison to normal cells.8–11 In addition, inhibition of glutaminase activity or glutaminase depletion blocked cancer cell growth.12 As the importance of glutamine metabolism in cancer progression, great efforts have been made to target this metabolic pathway for cancer treatment. The gene discussed is GLS; the disease is cancer.