ACTA1 and chronic obstructive pulmonary disease: Interestingly, α-SMA positive cells were not present in every patient, whereas Tn-C positivity, at least in basal epithelial cells, was observed in every patient studied, which may indicate that the basal cells might be able to produce Tn-C in large airways even in healthy lung, and that myofibroblasts may be responsible for the production of the excess of Tn-C in patients with COPD.