Substrate-recognition component of the Cul7-RING(FBXW8) ubiquitin ligase complex, which mediates the ubiquitination and subsequent proteasomal degradation of target proteins (PubMed:17205132, PubMed:18498745, PubMed:21572988, PubMed:24362026, PubMed:35982156). The Cul7-RING(FBXW8) complex mediates ubiquitination and consequent degradation of GORASP1, acting as a component of the ubiquitin ligase pathway that regulates Golgi morphogenesis and dendrite patterning in brain (PubMed:21572988). Mediates ubiquitination and degradation of IRS1 in a mTOR-dependent manner: the Cul7-RING(FBXW8) complex recognizes and binds IRS1 previously phosphorylated by S6 kinase (RPS6KB1 or RPS6KB2) (PubMed:18498745). The Cul7-RING(FBXW8) complex also mediates ubiquitination of MAP4K1/HPK1: recognizes and binds autophosphorylated MAP4K1/HPK1, leading to its degradation, thereby affecting cell proliferation and differentiation (PubMed:24362026). The Cul7-RING(FBXW8) complex also mediates ubiquitination of phosphorylated cyclin-D1 (CCND1) (PubMed:17205132). The Cul7-RING(FBXW8) complex is however not a major regulator of CCND1 stability during the G1/S transition (By similarity). Associated component of the 3M complex, suggesting that it mediates some of 3M complex functions (PubMed:24793695). {ECO:0000250|UniProtKB:Q8BIA4, ECO:0000269|PubMed:17205132, ECO:0000269|PubMed:18498745, ECO:0000269|PubMed:21572988, ECO:0000269|PubMed:24362026, ECO:0000269|PubMed:24793695, ECO:0000269|PubMed:35982156}. This is the function of FBXW8 (F-box and WD repeat domain containing 8, ENSG00000174989).