WWC1 and neurodegenerative disease: Evidence indicates that KIBRA and Rab27a are predominantly expressed in the brain, and KIBRA-mediated inhibition of Rab27a ubiquitination and degradation promotes the secretion of exosomes, suggesting that decreased Rab27a ubiquitination may be involved in the initiation and progression of neurodegenerative diseases (Song et al., 2019).