Previous studies have implicated a role for amphiregulin in psoriasis, an autoimmune disease characterized by hyperproliferative epidermis.47–49,58 Our work with amphiregulin in axolotl limbs is in line with these findings as it is sufficient to promote epidermal thickening in intact limbs (Fig. 7a and Supplementary Fig. 6a–d) and promotes increased cell proliferation in wound epidermis (Fig. 7b–e). This evidence concerns the gene AREG and autoimmune disease.