Model for regulation of exosome secretion by cortactin, Rab27a, and coronin. (A) Cortical branched actin helps create MVE docking sites, such as invadopodia (Hoshino et al., 2013b) at the PM. (B) Cortactin stabilizes branched actin (Weaver et al., 2001), which enhances MVE docking. (C) Coronin antagonizes cortactin at actin branch points (Cai et al., 2008), leading to destabilization of actin branches and fewer MVE docking sites. Rab27a opposes this antagonism by inhibiting coronin binding to invadopodia-associated actin (Fig. 6, C–E), potentially by sequestration (Kimura et al., 2010; Yokoyama et al., 2011).