One of the most tumorigenic heterodimersis formed between HER2 and HER3, which strongly activates the PI-3K/Aktpathway, a well-known signaling pathway driving tumorigenesis.4 The members of the HER family might be abnormallyactive in different cancers, sometimes as a consequence of upregulatedexpression, and may then serve as targets for tumor-specific deliveryof cytotoxic drugs for these specific subsets of patients. The gene discussed is ERBB3; the disease is cancer.