SIRT1 and laryngotracheoesophageal cleft: Another in vivo study showed that BCX exerts protective effects against LC and emphysema by reducing nicotine/NNK-induced Sirtuin 1 (SIRT1) mRNA, reducing RARβ and p53 mRNA levels and increasing serine-threonine kinase (AKT) phosphorylation levels [75].