CD9 and Familial prostate cancer: In a narrower context related to prostate cancer treatment, namely the diminished availability of androgens caused by androgen-deprivation therapy, prostate cancer LNCaP cells cultured in the presence of androgens secrete exosomes enriched in CD9, which in turn induce the proliferation of androgen-deprived LNCaP cells (Soekmadji et al., 2016).