The function of RNF13 (ring finger protein 13, Ensembl gene identifier ENSG00000082996) is as follows. E3 ubiquitin-protein ligase that regulates cell proliferation (PubMed:18794910, PubMed:23378536, PubMed:30595371). Involved in apoptosis regulation (PubMed:23378536, PubMed:30595371). Mediates ER stress-induced activation of JNK signaling pathway and apoptosis by promoting ERN1 activation and splicing of XBP1 mRNA (PubMed:23378536, PubMed:30595371). Also involved in protein trafficking and localization (PubMed:24387786). {ECO:0000269|PubMed:18794910, ECO:0000269|PubMed:23378536, ECO:0000269|PubMed:24387786, ECO:0000269|PubMed:30595371}.