SOX9 and intrahepatic cholangiocarcinoma: Moreover, by tracing the process of RAS-induced carcinogenesis in hepatocyte organoids, hepatocytes gradually expressed cholangiocyte markers, such as CK7, CK19, SOX9, and SPP1, and began to possess intracellular cavities filled with microvilli, a hallmark ultrastructure of intrahepatic cholangiocarcinoma (ICC) cells (Sun et al., 2019).