Most tumour cells expressed human nuclear antigen (HuNU), confirming their xenograft origin. They also expressed cone-related proteins (CRX, cone arrestin, L/M-opsin, RXRγ, CD133 and IRBP) and proliferation-related proteins (Ki67, SKP2, p107 and cytoplasmic p27) but lacked Rb. Tumours had elements resembling Flexner–Wintersteiner rosettes (asterisks) and fleurettes (daggers). Scale bars, 40 μm. Data are representative of three independent experiments.