It is well established that CCSP is expressed in non-ciliated Clara cells in the airways. CCSP which is widely used as a Clara cell marker is a cytoplasmic secretory protein [3] . Figure 2A revealed intense immunorectivity along the lining of mouse TB. Recently, Wong AP et al. was able to isolate CCSP + cells from bone marrow using flow cytometry [15] . Therefore, we postulated that CCSP may be expressed not only in the cytoplasm, but also in the cell membrane of Clara cells. To obtain evidence for this, we used the well-known cell membrane marker pan-Cadherin [18] . Indeed, in high magnification photomicrographs we were able to demonstrate co-expression with pan-Cadherin in the cell membrane using confocal microscope ( Figure 2B) . These data suggested a possibility for isolating living Clara cells by flow cytometry sorting and lead us to develop the protocol outlined in this study.