CD274 and non-small cell lung carcinoma: Additionally, to double-check the absence of p53 in PD-L1 inhibition, we treated NSCLC cells with PFT-α, a specific inhibitor of p53 transcription activity and its combination treatment with nobiletin, and then analyzed the protein levels of p53, phospho-MDM2, and PD-L1 expression (Figure S3A).