ANO1 and chronic obstructive pulmonary disease: In addition to PH, higher production and accumulation of mucus in airways was observed in COPD patients; in fact, Singh and colleagues verified that in the lung tissue of COPD smokers, the expression levels of Anoctamin 1 (ANO1), a calcium-activated chloride channel present in the airway epithelium, involved in mucus secretion and regulation of vascular contraction, were higher compared to the control [47].