The ON sequence selected for thisstudy has been previously used as a model sequence in the assemblyof SNAs.2 It has been shown to downregulateHER2, overexpression of which is associated with various cancer typesas it promotes malignant cell growth and differentiation.33,34 HER2 downregulation has been shown to inhibit proliferation andinduce apoptosis in HER2 expressing cells.35−38 The antisense activities of MSNA-PS and MSNA-PO were confirmed invitro by Western blot analysis using human breast cancer(BT-474) cells. The gene discussed is ERBB2; the disease is breast cancer.