DRD2 and esophageal squamous cell carcinoma: Because one member of G protein-coupled receptors (GPCRs)-platelet activating factor receptor (PAFR) interacted with Tyk2 and JAK2 to form protein complex and then persistently activate JAK2/STAT3 in ESCC cells,24 we hypothesized whether some members of GPCRs can participate into PCs-mediated assembly of Tyk2/JAK2 complex and the activation of JAK2/STAT3 pathway, and selected 22 GPCRs, including adenosine receptor A1 (ADORA1), ADORA2A, ADORA2B, dopamine receptor D1 (DRD1), DRD2, DRD3, et al for further co-IP assays.