RAB40A is a small GTPase that functions as a substrate-recognition component of the ECS(RAB40A) E3 ubiquitin ligase complex, mediating ubiquitination and proteasomal degradation of target proteins 1. As a member of the Rab protein family, RAB40A regulates intracellular membrane trafficking and localizes to the perinuclear recycling compartment and endosomal compartments, suggesting involvement in receptor recycling and vesicular transport 2. Within the ECS(RAB40A) complex, RAB40A specifically mediates Lys-48-linked ubiquitination of RHOU, thereby inhibiting focal adhesion disassembly during cell migration 1. RAB40A is located on the X chromosome X is among genes implicated in neurological disease; deletions encompassing RAB40A associate with early-onset neurological disease traits including hypotonia and intellectual disability in females 3. In type 1 diabetes pathology, RAB40A expression is significantly altered in circulating exosomes of pediatric patients, with levels normalizing following insulin therapy, suggesting involvement in T1D-related pathological mechanisms 4. These findings indicate RAB40A plays critical roles in cell adhesion regulation, vesicular trafficking, and immune-related disease processes, making it a potential therapeutic target for conditions involving aberrant protein degradation or cellular adhesion dynamics.