TWEAK is a potent inducer of HPC proliferation [16,17,18]; in particular, it has a selective mitogenic effect for the liver progenitor ("oval") cells in rodents, while an increased Fn14 expression in chronic hepatitis C and related diseases suggests a similar role for the TWEAK/Fn14 pathway in humans [19]. The gene discussed is TNFSF12; the disease is chronic hepatitis C virus infection.