This phenomenon has been seen with other SBPs, notably the HER2-binding Affibody (ZHER2:342) that alone was non-toxic toward both SKBR3 breast cancer cells and SKOV3 ovarian cancer cells,21 and also with monovalent HER2-binding DARPins and BT474 cells.26 The gene discussed is ERBB2; the disease is ovarian carcinoma.