PKR, also known as Protein Kinase R or double-stranded RNA-dependent protein kinase, is a serine/threonine catalytic enzyme that plays a crucial role in innate immune responses against viral infections. It is an interferon-induced kinase that can be activated by double-stranded RNA (dsRNA), a common byproduct of viral replication. Once activated, PKR phosphorylates the eukaryotic initiation factor 2伪 (eIF2伪), which inhibits protein synthesis and viral replication. Additionally, PKR can activate the NF-魏B signaling pathway, enhancing the expression of antiviral genes. Beyond its antiviral functions, PKR is involved in various cellular processes, including apoptosis, cell growth, and differentiation. Its dysregulation has been implicated in several diseases, including cancer, making it a potential therapeutic target.