However, the specific mechanisms underlying PD-L1 expression are not fully understood: in the context of tumor cells, its expression is associated with the activation of the Mitogen-Activated Protein Kinase (MAPK) and Phosphoinositol-3 Kinase (PI3K) pathways (42); whereas in inflammatory conditions, interferons (IFNs) and the Signal Transducer and Activator of Transcription 1/Interferon Regulatory Factor 1 (STAT 1/IRF 1) pathway appear to be the primary inducers. The gene discussed is CD274; the disease is neoplasm.