CD274 and lip and oral cavity carcinoma: In an in vitro oral cancer model, PD-L1 expression was significantly upregulated; however, this expression markedly decreased upon triptolide treatment, which further inhibited tumor growth, confirming that this inhibition was mediated through downregulation of JAK/STAT1 and HER2/phosphoinositide 3-kinase/Akt signaling pathways [239].