HESX1 and neoplasm: The mouse models (both Hesx1- and Sox2-driven36,37), while they allow the study and manipulation of tumorigenesis, lack some features of human aCP: for instance, they do not develop a defined palisading layer of epithelial cells at the invading edge of the tumour, nor do they show calcification or the anucleated ghost cells (wet keratin) that are pathognomonic for human aCP.