Increased PERK levels in the tumor tissues are associated with a poor prognosis for patients with prostate cancer [56], pancreatic duct adenocarcinoma (PDAC) [57], kidney renal papillary cell carcinoma, gliomas, breast carcinoma, and thyroid carcinoma [58], but determined a favorable prognosis for head and neck squamous cell carcinoma (HNSCC) [58] (Table 2). This evidence concerns the gene EIF2AK3 and head and neck squamous cell carcinoma.