IL15 and breast cancer: However, it was later shown that exosomes derived from NK-92 MI cells had antitumor effects on melanoma both in vitro (B16F10 cells) and in vivo (8), and those isolated from IL-2/IL-15–activated NK cells showed cytotoxicity in breast cancer cell lines (MDA-MB-231/F and MCF-7) (12, 15, 16).