The invention relates to anti-HER3 antigen binding proteins, eg. anti-HER3 antibodies, that bind to the beta-hairpin of HER3, methods for selecting these antigen binding proteins, their preparation and use as medicament.本發明係關於結合至HER3之β-髮夾結構之抗HER3抗原結合蛋白(例如抗HER3抗體)、選擇該等抗原結合蛋白之方法、其製備及作為藥劑之用途。