E3 ubiquitin ligase that plays a role in several processes including innate antiviral immnity, cell migration and chemotaxis. Acts as a 'Lys-63'-specific ubiquitin ligase for MAPK1/ERK2 and MAPK3/ERK1, promoting their activation by facilitating their interaction with MAP2K1 and MAP2K2. Plays also a role in cell migration and chemotaxis by acting as a stable focal adhesion component upon recruitment by multi-adapter protein paxillin/PXN. Functions in the RIGI-mediated interferon induction pathway upstream or at the level of MAVS. Inhibits NF-kappa-B activation by turnover of 'Lys-63'-linked ubiquitination of MAP3K7/TAK1. Mechanistically, prevents TRIM8 cytoplasmic translocation and thus inhibits TRIM8-mediated 'Lys-63'-linked polyubiquitination of MAP3K7/TAK1 in the cytoplasm. Plays also an important regulatory effect on the activation of hepatic stellate cells (HSCs).