Heterogeneous LMP1 expression within an ENKTL tumour. Upper photomicrograph: EBER in-situ hybridisation on a 4 μm formalin-fixed, paraffin-embedded ENKTL tissue section (optical magnification x200). Courtesy of Dr Simon O'Connor, Department of Histopathology, Nottingham University Hospitals. Lower photomicrograph: Immunohistochemical stain of a 4 μm formalin-fixed, paraffin-embedded ENKTL tissue section using CS1-4 (anti-LMP1) antibodies. The image was captured with a Nikon CoolpixE995 digital camera, via a Nikon Eclipse E400 microscope (optical magnification, ×400).