The heregulin-dependent HER2-HER3 heterodimer was reported to be the most oncogenic HER dimer [13], and this dimer induced resistance of colorectal cancer to anti-EGFR antibodies and of non-small cell lung cancer to EGFR tyrosine kinase inhibitors [14, 15]. The gene discussed is EGFR; the disease is non-small cell lung carcinoma.