Secondly, the activation of receptors mediating these signalling pathways [i.e. G-protein coupled bile acid receptor 1 (GPBAR1) and sphingosine 1 phosphate receptor 2 (S1PR2), or nuclear factor kappa B (NF-κB)] in CCA tissue samples is enhanced (82, 86–89). Here, S1PR2 is linked to cholangiocarcinoma.