GLS and cancer: Two alternative possibilities warrant further investigation in terms of selenite’s toxic mechanism in A549 spheroids, e.g., (1) inhibition of glutaminolysis via enhanced GLS1 degradation [52]; (2) altered detoxification mechanism involving direct interaction of selenite with GSH to form selenodiglutathione (GSSeG) [53] and subsequent efflux of GSSeG from cancer cells [54].