Ubiquitin-specific protease 9x (Usp9x), also known as ubiquitin carboxyl-terminal hydrolase FAF-X or FAM, is a deubiquitinase that acts as an important component in TGF-beta and bone morphogenetic protein signalling. It specifically deubiquitinates monoubiquitinated SMAD4, opposing the activity of E3 ubiquitin-protein ligase TRIM33 []. It is involved in axonal growth and neuronal cell migration []. Loss of Usp9x disrupts cortical architecture, hippocampal development and TGFbeta-mediated axonogenesis [].
