GDF15 and hepatocellular carcinoma: We also found a reduced expression of ATF5 after sirolimus exposure in our EHE models, which likely contributed to GDF-15 inhibition, in accordance with a previous report indicating that RNAi-mediated downregulation of ATF5 caused a reduced expression of GDF-15 in hepatocellular carcinoma cells (33) and also confirmed in our EHE cell line.