Ligand of the EGF receptor/EGFR and ERBB4. Stimulates EGFR and ERBB4 tyrosine phosphorylation (PubMed:9990076). Contributes to inflammation, wound healing, tissue repair, and oocyte maturation by regulating angiogenesis and vascular remodeling and by stimulating cell proliferation (PubMed:24631357). Interacts with EGFR and ERBB4. By angiotensin II, endothelin-1 and alpha-thrombin. Strongly induced in ovarian granulosa cells by FSH stimulation.