To this end, we conclude that the conjugation reaction between the αEGFR-mAB coupled to SMCC-protamine and a 32x excess of SMCC-protamine which is combined with 10 mol siRNA per mol of IgG-conjugate yields an optimal formulation to bind, transport, internalise and consequently liberate functionally effective siRNA to EGFR-expressing tumour cells. The gene discussed is EGFR; the disease is neoplasm.