GPBAR1 and gastric cancer: It is noted that transfection of gastric cancer cells with TGR5 inhibited NF-κB activity in the absence of ligand, suggesting that TGR5 may suppress NF-κB activity without the addition of exogenous ligand, possibly resulting from the fact that GPCRs have constitutive activity as previously reported (Tao, 2008; Senft et al., 2011; Wang et al., 2011).