PDCD1 and nasopharyngeal carcinoma: NFATC1 is reported to regulate PD-1 expression following T cell activation,39 which is consistent with the upregulated PD-1 expression observed in CD4+ Tconv-3 and implicates NFATC1 as a potential regulator of CD4+ Tconv cells in their way to become dysfunctional in NPC.