Furthermore, Rab39B, one of the two isoforms of the Rab39 protein regulating basolateral exosome trafficking (Matsui et al., 2022), is a causative gene product of Parkinson’s disease (Wilson et al., 2014; Lesage et al., 2015; Mata et al., 2015), further fortifying the links found between Parkinson’s disease and exosomes (Danzer et al., 2012; Toro et al., 2015; Guo et al., 2020; Pinnell et al., 2021; Kluge et al., 2022; Li et al., 2022), and suggesting another link to those from polarized cells. The gene discussed is RAB39B; the disease is Parkinson disease.