TTF1 and lung cancer: To do this, thyroid transcription factor-1 (Ttf-1) which is expressed in the lung epithelial cells (Lazzaro et al., 1991), was used to mark lung cancer cells, and Cd68 stain was employed to mark macrophages which can produce Cxcl13 in inflammatory lesions with lymphoid neogenesis (Carlsen et al., 2004).