3 Extra staining of tumour biopsies The tumour biopsies may be stained with markers for proliferation (e.g. KI 67), apoptosis (e.g. M30), hypoxia (e.g. HIF, CA 9, Glut 1 and 3) and others (e.g. EGFR and EGFRvIII), in order to correlate these measurements with response.