To further demonstrate the direct role of NKG2D in trastuzumab-mediated ADCC of HER2 positive breast carcinoma cells, PBMCs from healthy donors were collected, treated with prostaglandin-E2 (PGE2) for 24 hours to force NKG2D down-modulation [13], and used in ADCC assay against BT474 cells. Here, ERBB2 is linked to breast carcinoma.