CDKN1A and idiopathic pulmonary fibrosis: In IPF an increase in SIRT6 expression in airway epithelial cells, which may be induced in vitro by TGF-β, although overexpression of SIRT6 inhibits cellular senescence in these cells via proteasomal degradation of p21 and myofibroblast differentiation to fibroblasts (Minagawa et al, 2011).