In silico analysis of claudin gene expression in various normal and neoplastic tissues. 266 SAGE libraries were examined for the expression of all 21 CLDN genes using SAGE Genie . SAGE data was compiled from both normal and cancerous tissue, and analyzed using dChip software http://www.dchip.org program, which assigned darker shades of red to higher number of tags. GAPDH and ACTN levels were also analyzed as controls. While some CLDN genes are ubiquitously expressed, others exhibit highly tissue specific patterns. A detailed spreadsheet of the data is available as supplementary information.