We coupled classic control siRNA that was labeled with Alexa 488 and/or Alexa 555, respectively to the anti-EGFR-antibody cetuximab via sulfo-SMCC-protamine and treated the colorectal cancer (CRC) cell lines DLD1, SW480 and HT29 with these antibody-siRNA complexes in vitro. The gene discussed is EGFR; the disease is colorectal carcinoma.