CS/DS is implicated in several cancer-promoting processes, such as cell proliferation and metastasis 3. DS-epi1, previously named SART2 (squamous cell carcinoma antigen recognized by T cell 2), is highly expressed in many tumours and cell lines 20. DS-epi1 expressed by cancer cells was recognized by HLA-A24-restricted and tumour-specific cytotoxic lymphocytes. Peptides from DS-epi1 were used in peptide-based immunotherapy phase I clinical trials for prostate cancer 67, glioblastoma multiforme 68 and hepatocellular carcinoma 69 with moderate success. We have established that DS-epi1 is not tumour specific because DS-epi1 is ubiquitously expressed in normal tissues 21. Squamous cell carcinoma from oesophagus contains epimerase activity that is increased four- to five-fold compared to normal oesophagus 13. DS-epi1 is localized both in stroma surrounding the tumour and in cancer cells. To investigate the role of IdoA, DS-epi1 was stably down-regulated in oesophagus squamous carcinoma cell lines using shRNA sequences. IdoA was shown to facilitate the binding of HGF to its receptor and was essential for cMET-dependent signalling 13 (Fig. 4F). In addition, DS-epi1 down-regulated cells displayed fewer cytoplasmic stress fibres than control cells. Furthermore,
