Interestingly, the distribution of eGFP and CC10 expression recapitulated the pattern observed during early lung development i.e. eGFP pos -CC10 pos cells separating eGFP pos -CC10 low from apparently newly formed eGFP neg -CC10 pos cells. The kinetics of appearance and relative localization of these cells within the tissues are consistent with the notion that they may represent sequential stages of development from the eGFP pos -CC10 low to the eGFP neg -CC10 pos phenotype.