The contribution of PPARδ in hepatocyte proliferation and HCC is still unclear and strongly discussed in literature; PPARδ knock out animals are characterized by a delay in LR exclusively in the early phases of LR (no data for late time points) [36], while PPARδ activation in HepG2 cells has been shown to both promote [19], [27], [37] and inhibit [28] cell proliferation, or even to have no influence [38]. This evidence concerns the gene PPARD and hepatocellular carcinoma.