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 (By similarity). Negatively regulates Wnt signaling, possibly by antagonizing the recruitment of AXIN1 to LRP6 (By similarity). Interacts with iRhom1/RHBDF1 and iRhom2/RHBDF2 (via cytoplasmic N-termini); this interaction leads to mutual protein stabilization. Interacts with ADAM17; this interaction is indirect and mediated by iRhom proteins (By similarity). Interacts with LRP6; this interaction affects LRP6-binding to AXIN1 (By similarity).