STAT3 and neoplasm: Several oncogenic signaling pathways, such as Akt/mTOR, JAK/STAT3, and EGFR/MAPK, or the loss or silencing of PTEN, ALK, and EGFR, are involved in the regulation of PD-L1 transcription, potentially leading to the upregulation of PD-L1 expression in tumor cells [227].