GYS1 and neoplasm: It has been reported that the hypoxic microenvironment in tumor cells induced the HIF1α-dependent transcriptional upregulation of glycogen synthesis enzymes, such as phosphoglucomutase1 (PGM1), glucose-1-phosphate uridylyltransferase (UGP2), glycogen synthase 1 (GYS1) and 1,4-α glucan branching (GBE1), leading to the accumulation of glycogen (Mole et al., 2009; Pelletier et al., 2012; Pescador et al., 2010; Shen et al., 2010).