Activates HECT domain-containing E3 ubiquitin-protein ligases, including NEDD4 and ITCH, and consequently modulates the stability of their targets. As a result, controls many cellular processes. Prevents chronic T-helper cells-mediated inflammation by activating ITCH and thus controlling JUNB degradation By similarity. In cortical neurons, mediates the ubiquitination of SLC11A2/DMT1 by NEDD4L, leading to down-regulation of the divalent metal transporter and protection of the cells from cobalt and iron toxicity. Modulates EGFR signaling through multiple pathways. In particular, may regulate the ratio of AKT1-to-MAPK8 signaling in response to EGF, acting on AKT1 probably through PTEN destabilization and on MAPK8 through ITCH-dependent MAP2K4 inactivation. As a result, may control cell growth rate.