Additionally, cancer cells can also express PD-L1 because of specific oncogenic signaling, such as RAS, which up-regulates its expression through a mechanism involving increases in PD-L1 mRNA stability [54], or the EML4-ALK fusion gene and mutant EGFR, which up-regulate PD-L1 by activating PI3K-AKT and MEK-ERK signaling pathways in NSCLC [55]. Here, CD274 is linked to non-small cell lung carcinoma.