Serine protease that cleaves beta-casein/CSN2 as well as several extracellular matrix (ECM) proteoglycans such as decorin/DCN, biglycan/BGN and fibronectin/FN1. Inhibits signaling mediated by TGF- beta family proteins possibly indirectly by degradation of these ECM proteoglycans (By similarity). May act as a tumor suppressor. Negatively regulates, in vitro, trophoblast invasion during placental development and may be involved in the development of the placenta in vivo. May also have a role in ovarian development, granulosa cell differentiation and luteinization (PubMed:21321049, PubMed:22229724). {ECO:0000250|UniProtKB:Q9D236, ECO:0000269|PubMed:21321049, ECO:0000269|PubMed:22229724}. This is the function of HTRA3 (HtrA serine peptidase 3, Ensembl gene identifier ENSG00000170801).