To judge whether determination of the CLCA2 protein expression status might be useful for distinguishing between SCC and ADC, we performed an immunohistochemical analysis using anti-CLCA2 polyclonal antibody in TMA sections containing cancerous tissues in 235 specimens of primary ADC of the lung and 161 specimens of primary SCC of the lung (Hamamatsu University Hospital, Japan). Here, CLCA2 is linked to AIDS dementia complex.