Cdc42 is one of the well studied Rho GTPases primarily known for the regulation of filopodia in cells. While most of the studies were focussed on the regulation of activation dynamics of Cdc42 by GEFS and GAPs, the mechanisms driving the proteostasis of Cdc42 remained unclear. Work from MSU, now unveiled the first E3 ubiquitin ligase of Cdc42. XIAP, an evolutionarily conserved member of the IAP family directly binds to Cdc42 and conjugates polyubiquitin chains to K166 of Cdc42 leading to proteasomal degradation. Silencing of XIAP led to enhanced filopodia in cells in a CDC42 dependent manner. Please use the link below to get full access to the story. https://www.nature.com/cddis/journal/v8/n6/full/cddis2017305a.html