PRKD3 and head and neck squamous cell carcinoma: Our previous studies determined that PKD3 can regulate PD-L1 expression.14 Moreover, PD-L1 is closely related to EMT in HNSCC.25 To verify whether PKD3 is involved in the regulation of EMT in OSCC, we first analysed the protein levels of PKD3, PD-L1 and EMT markers in OSCC cell lines and tissues using western blot and IHC.