CD274 and colon carcinoma: Oncogenic HRAS signaling was also capable of inducing PD-L1 mRNA and protein expression in the immortalized breast epithelial cell line MCF10A and the KRAS wild-type colon carcinoma cell line HKE-3 (Figures S1A and S1B), implying that induction of PD-L1 expression by RAS is not a tissue-specific or RAS-isoform-specific phenomenon.