OIP5 and neoplasm: More importantly, with trastuzumab treatment, tumor cells in si-NC-exo group grew faster than trastuzumab or si-OIP5-AS1#1-exo group (group 3 vs group 2 or group 4, respectively) (Figure 7a and b), suggesting that exosome-mediated transfer of OIP5-AS1 suppressed the cytotoxicity induced by trastuzumab treatment in vivo.