The function of ENSG00000115317 (HTRA2, HtrA serine peptidase 2) is as follows. [Isoform 1]: Serine protease that shows proteolytic activity against a non-specific substrate beta-casein (PubMed:10873535). Promotes apoptosis by either relieving the inhibition of BIRC proteins on caspases, leading to an increase in caspase activity; or by a BIRC inhibition-independent, caspase-independent and serine protease activity-dependent mechanism (PubMed:15200957). Cleaves BIRC6 and relieves its inhibition on CASP3, CASP7 and CASP9, but it is also prone to inhibition by BIRC6 (PubMed:36758104, PubMed:36758105). Cleaves THAP5 and promotes its degradation during apoptosis (PubMed:19502560). {ECO:0000269|PubMed:10873535, ECO:0000269|PubMed:15200957, ECO:0000269|PubMed:19502560, ECO:0000269|PubMed:36758104, ECO:0000269|PubMed:36758105}. [Isoform 2]: Seems to be proteolytically inactive. .