GREM1 and primary biliary cholangitis: By RTqPCR of human explant livers of different aetiologies (all fibrosis stage F4), we observed a 4.8- to 9.8-fold increase in GREM1 mRNA expression in MASH, ALD, PBC, and PSC liver tissues when compared to donor livers (n=13–15 each, Figure 1C).