To confirm whether the E1A protein reduces the expression of the ErbB2 protein, the ErbB2-overexpressing breast cancer cell, BT474, was infected with oAd or oAd/shErbB3 at MOI of 0.5–2; then, the expressions of E1A and ErbB2 were measured by Western blotting. The gene discussed is ERBB2; the disease is breast carcinoma.