EGFR and Familial prostate cancer: According to the analysis of the exosomal miRNA profile and the EGFR signaling change based on EWI‐2 depletion, we demonstrate that exosomal miR‐3934‐5p, which was confirmed as an EGFR inhibitor, might be functionally delivered to parental prostate cancer cells, possibly in an autocrine/paracrine manner, and further affect the EGFR‐MAPK‐ERK signaling of other cancer cells.