YAP1 and neoplasm: CircYAP1 binds directly to the YAP1 (yes1 associated transcriptional regulator) protein, preventing its phosphorylation which enhances YAP1 nuclear import, where interactions with transcription factor 4 (TCF4) promotes the expression of the immune checkpoint inhibitor PD-L1 (CD274), leading to immune evasion and tumor progression [143].