KRAS and pulmonary emphysema: K-RAS mutations have been detected in approximately 20% of NSCLC, particularly adenocarcinomas.25 Phosphorylated ERK has been detected in up to one-third of NSCLCs with an inconsistent association with prognosis.22, 26, 27 Elevated phosphorylated ERK has also been reported in emphysema compared with healthy lung tissue,28 and it is postulated that constitutive ERK activation may be a critical event in emphysema progression.29, 30 Evidence also points to activation of the PI3K/AKT/mTOR pathway in the pathogenesis of COPD.31, 32