GLDC and neoplasm: In this sense, cysteine has been shown to be elevated in various types of cancer including LC (Gamcsik et al., 2012; Krepela et al., 1997), and the glycine decarboxylase, the enzyme responsible for glycine degradation, has been related to tumor‐initiating cells in NSCLC (Berezowska et al., 2017; Lin et al., 2017).