The present invention relates to methods for the inhibition, of the gene product of the neu oncogene, p185neu tyrosine kinase. Over-expression of the neu oncogene leads to chemoresistance. The methods disclosed involve the novel use of E1A and/or LT in combination with chemotherapeutic drugs to treat carcinoma. Furthermore, E1A surprisingly potentiates the antineoplastic effects of the chemotherapeutic agents. The inventors propose that E1A sensitizes cancer cells such that they become amenable to treatment by chemotherapeutic drugs.