To this aim, we evaluated the levels of two enzymes involved in GSH biosynthesis, namely GSH synthetase (GSS) that catalyzes the second step of de novo GSH biosynthesis and has been found upregulated in several cancer types [54], and GSH reductase (GSR), a flavoprotein enzyme that regenerates GSH from GSSG [4]. The gene discussed is GSR; the disease is cancer.