The function of PRF1 (perforin 1, ENSG00000180644) is as follows. Pore-forming protein that plays a key role in granzyme- mediated programmed cell death, and in defense against virus-infected or neoplastic cells (PubMed:20889983, PubMed:21037563, PubMed:24558045, PubMed:9058810, PubMed:9164947). Plays an important role in killing other cells that are recognized as non-self by the immune system, e.g. in transplant rejection or some forms of autoimmune disease (PubMed:9058810). Can insert into the membrane of target cells in its calcium-bound form, oligomerize and form large pores (PubMed:20889983, PubMed:21037563). Promotes cytolysis and apoptosis of target cells by mediating the passage and uptake of cytotoxic granzymes (PubMed:20038786, PubMed:20225066, PubMed:24558045, PubMed:32299851). Facilitates the delivery of cationic cargo protein, while anionic or neural proteins are not delivered efficiently (PubMed:24558045). Perforin pores allow the release of mature caspase-7 (CASP7) into the extracellular milieu (By similarity). {ECO:0000250|UniProtKB:P10820, ECO:0000269|PubMed:20038786, ECO:0000269|PubMed:20225066, ECO:0000269|PubMed:20889983, ECO:0000269|PubMed:21037563, ECO:0000269|PubMed:24558045, ECO:0000269|PubMed:32299851, ECO:0000269|PubMed:9058810, ECO:0000269|PubMed:9164947}.