JAK1 and cholangiocarcinoma: In this respect, it is interesting that our two groups of PDXs, which appear to respond differently to paracrine signals from MSCs, bear some relationship to the molecular subtypes of CCA previously described, with ERBB2, EGFR and MET considered markers of the proliferative molecular subclass of CCA and JAK1, which is part of the STAT3 signalling pathway, associated with the inflammatory molecular subclass of CCA (Sia et al., 2013).