GLS and cancer: Furthermore, sequential glutaminase and glutamate dehydrogenase reactions produce ammonia (NH3) and ammonium (NH4+), respectively, which is considered a cell toxic by-product which requires scavenging through urea; however, ammonia is also a major diffusible autophagy inducer [21], which could therefore help cancer cells increase fitness by eliminating damaged and potentially toxic macromolecules and organelles.