CD274 and non-small cell lung carcinoma: First, (IIA) the PD-L1 protein may be up-regulated after EGFR/RAS/MAPK pathway activation, either by over-expression of wild types of EGFR, such as in head and neck carcinoma [16], or by activating mutations of RAS and EGFR, which is more seen in non-small cell lung carcinoma (NSCLC) [33,34,35,36].