ENTPD1 and head and neck squamous cell carcinoma: Here, we assessed the expression of PD-1 and CD39 in circulating memory (CD45RA-) conventional (Tconv; FOXP3-) CD4 T cells (Supplementary Figure S1) from head and neck squamous cell carcinoma (HNSCC) and cervical cancer (CC) patients and from healthy donors (HDs).