May modulate activity of cullin-RING E3 ubiquitin ligase (CRL) complexes (PubMed:21778237). Negatively regulates cell proliferation. Negatively regulates cell cycle G2/M phase transition probably by transactivating p21/CDKN1A through the p53/TP53-independent signaling pathway. Involved in kidney proximal tubule morphogenesis (By similarity). Down-regulates activation of NF-kappa-B (PubMed:15799966). Interacts (via COMM domain) with COMMD1 (via COMM domain). Interacts with RELA, RELB, NFKB1/p105. Interacts with CCDC22, CCDC93, SCNN1B, CUL2, CUL3, CUL4A, CUL4B, CUL7. Highly expressed in heart, stomach, jejunum, kidney, liver, and adrenal gland. Expression was generally higher in adult organs than in fetal tissues, particularly in heart, kidney, and liver.