May modulate activity of cullin-RING E3 ubiquitin ligase (CRL) complexes. 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. Down-regulates activation of NF-kappa-B. 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.