Peng et al. [53] tested the rate of pulmonary vascular endothelial cell apoptosis in lung tissue of eleven patients with COPD and ten patients with non-COPD squamous cell lung cancer, measured the expression of mitochondrial transcription factor (mtTFA) mRNA and protein and methylation of the mtTFA promoter. The gene discussed is TFAM; the disease is chronic obstructive pulmonary disease.