RIPK3 and metabolic dysfunction-associated steatohepatitis: Thus, the cytokeratin 18 (CK18) fragment and receptor-interacting serine/threonine-protein kinase 3 (RIPK3) or mixed lineage kinase domain-like protein (MLKL) are often used as the diagnostic biomarkers in NASH because CK18 is released from apoptotic hepatocytes and RIPK3 and MLKL, are upregulated in necroptosis [24,25].