CCL5 and breast cancer: Trastuzumab-induced NK cell activation against SKBR3, BT474 and HC1954 HER2-positive breast cancer cells resulted in the secretion of CCL5, IFN-γ and the consequent production of CXCL9 and CXCL10, as analysed by ELISA in cell-free coculture supernatants (Fig. 2A).