FNDC5 and cancer: Although more studies to support exosomal packaging and release of important myokines like irisin, IL-6, and myonectin are desired, the growing evidence of muscle EV secretion and remarkable encapsulation of muscle-specific biologic contents (transferable to various cell types and also implicated in cancer progression) (Singh et al., 2016; Wang et al., 2016; Li et al., 2018; Xu X. et al., 2018; Krishn et al., 2019) provide substantial cues for further investigations.