GPN1 and head and neck squamous cell carcinoma: GPN1 protein levels were significantly different across several cancers, including glioblastoma (GBM), head and neck squamous cell carcinoma (HNSC), kidney renal clear cell carcinoma (KIRC), HCC, ovarian serous cystadenocarcinoma (OV), and pancreatic adenocarcinoma (PAAD).