Compared with its role in the nervous system, SERT regulation in intratumoral T cells differs in three key aspects: (1) highly dynamic expression, (2) an autocrine and paracrine serotonin axis, and (3) distinct 5-HT receptor signaling (Table S2).41,42 These findings provide fundamental insights into the molecular network governing T cell antitumor immunity and could guide the development of next-generation cancer immunotherapy. This evidence concerns the gene SLC6A4 and cancer.