SOX9 and fatty liver disease: This widespread occurrence is consistent with previous isolated observations, such as the high Hes1/HNF4α frequency seen in metabolic dysfunction-associated fatty liver disease (MAFLD) and metabolic dysfunction-associated steatohepatitis (MASH)41 and the co-expression of Sox9/HNF4α in several mouse models12,42 as well as lineage-tracing data showing that full conversion of hepatocytes into BECs is exceedingly rare12,14.