FOS and chronic obstructive pulmonary disease: We noticed that some genes, such as FOS, CYR61 and CTGF, were upregulated in PBMCs from patients with either stable COPD or AECOPD, consistent with the lung tissue gene expression profiles of patients with COPD or smokers, in whom the genes were expressed mainly in alveolar epithelial cells, airway epithelial cells and stromal and inflammatory cells [14].