CDKN1A and bronchiectasis: The percentage of positively stained cells was markedly lower for SIRT1 (median: 25.1 vs. 57.2%, p < 0.05) and nominally lower for p16 (median: 40.0 vs. 45.1%) and p21 (median: 28.9 vs. 35.9%) in patients with bronchiectasis than in disease controls (p > 0.05) (Supplementary Table 4).