Promotes the cell surface stability of iRhom1/RHBDF1 and iRhom2/RHBDF2 and prevents their degradation via the endolysosomal pathway. By acting on iRhoms, involved in ADAM17-mediated shedding of TNF, amphiregulin/AREG, HBEGF and TGFA from the cell surface (PubMed:29897333, PubMed:29897336). Negatively regulates Wnt signaling, possibly by antagonizing the recruitment of AXIN1 to LRP6 (PubMed:19572019). {ECO:0000269|PubMed:19572019, ECO:0000269|PubMed:29897333, ECO:0000269|PubMed:29897336}. This is the function of FRMD8 (FERM domain containing 8, ENSG00000126391).