PERP and breast cancer: Interestingly, unlike the case with EVs, trastuzumab did not upregulate all of the indicated proteins in the breast cancer cells themselves: the drug upregulated RAB10 and PERP in BT-474 cells (Fig. 6d, e) but downregulated ITB1 (Fig. 6a) and did not change the levels of GNAS2 and GNA13 in the cells (Fig. 6b, c).