PYGL and head and neck squamous cell carcinoma: Our research findings along with the biological functions of the four metabolic biomarkers were summarized in Fig. 3H. Collectively, PYGL, the key element of the glycogen degradation process, was finally chose as the core biomarker of our research, for it was connected with high METArisk, led to poor prognosis, and was increasingly expressed in tumor at both transcriptional and translational level of HNSCC samples, which might sever as the driving factor for tumor-promoting cell metabolism reprogramming.