PIK3CA and lung adenocarcinoma: The MAPK signaling pathway exhibits the highest number of target connections (hsa004010, degree = 44), followed PI3K-Akt pathway (hsa04020, degree = 41), Chemical carcinogenesis-receptor activation signaling pathway (hsa05207, degree = 35), PD-L1 expression and PD-1 checkpoint pathway in cancer (hsa05235, degree = 28), and toxicity target-enriched IL-17 signaling pathway (hsa05235, degree = 22), etc. MAPK pathway activity plays a key role in EGF-and IFNγ-induced PD-L1 expression in lung adenocarcinoma (Stutvoet et al., 2019).