Growth factor- and cytokine-driven pathways governing liver stemness and differentiation

Figure 1 Schematic illustration of the major signaling pathways and biological activities induced by hepatocyte growth factor and epidermal growth factor receptor ligands in liver progenitor cells. HGF: Hepatocyte growth factor; EGF: Epidermal growth factor; TGF: Transforming growth factor; STAT: Signal transducer and activator of transcription; PI3K: Phosphoinositide 3-kinase; NF-κB: Nuclear factor κB; mTOR: Mammalian target of rapamycin; MEK: Mitogen-activated protein kinase kinase; ERKs: Extracellular-signal-regulated kinases.

Figure 2 Overview of the major signaling pathways, and their cellular effects, induced by transforming growth factor-β in liver cells. TGF: Transforming growth factor; EGFR: Epidermal growth factor receptor; ELF: Embryonic liver fodrin; TACE: Tumor necrosis factor-converting enzyme.

Figure 3 Wnt/β-catenin signaling. Left figure shows how β-catenin is pushed to degradation in the absence of Wnt ligand. Right figure shows how in the presence of Wnt, β-catenin regulates gene expression. TCF: T-cell factor; LRP: Low density lipoprotein receptor-related protein; APC: Adenomatous polyposis coli; CK1: Casein kinase 1; GSK: Glycogen synthase kinase.