CDKN1A and chronic obstructive pulmonary disease: Our studies show that, in end-stage COPD and IPF tissues, bronchoalveolar epithelial progenitor cells display a lesion-associated rise of LGR6 levels, which is followed by an overall increased expression of canonical Wnt-related markers, total β-catenin and glutamine synthetase and by the expression of senescence-associated markers p21 and p16 in areas of aberrant tissue regeneration.