To determine if the increased IFN-γ expression was a result of activation of PBMCs after their engagement with cancer cells through trastuzumab Fc, we first inactivated cancer cells with 4% paraformaldehyde (PFA); the inactivated BT474 cells were then co-cultured with PBMCs in the presence or absence of trastuzumab for 24 h; and IFN-γ mRNA levels in live PBMCs were determined by qPCR. Here, IFNG is linked to cancer.