HIF1A and cancer: Furthermore, PD-L1 expression is intricately linked to a network of regulatory mechanisms involving hypoxia-inducible factor 1 alpha (HIF-1α), vascular endothelial growth factor (VEGF), epidermal growth factor receptor (EGFR), and nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), all of which play significant roles in cancer progression, immune evasion, and response to therapy.