ERBB2 and neoplasm: As demonstrated by Levy and colleagues, stimulation of 4-1BB on natural killer (NK) cells promotes their cytotoxic potential and enhances antibody (Ab)-dependent cell-mediated cytotoxicity (ADCC) of anti-CD20-, anti-EGFR-, or anti-human epidermal growth factor receptor 2 (HER2)-coated tumor cells (Kohrt et al., 2011, 2012, 2014).