Further studies have shown that cathepsin S is markedly up-regulated by endothelial cells during tumour angiogenesis [12], [13] and compellingly, in a murine pancreatic islet carcinoma model (RIP1-Tag2), cathepsin S knockout mice had a significant reduction in tumour-associated angiogenic switching and neovascularisation [14]. The gene discussed is CTSS; the disease is neoplasm.