In line with these findings, we have previously demonstrated an interesting role of Nerve Growth Factor (NGF) and its receptors Tropomyosin-related kinase A (TrKA) and neurotrophin receptor p75 (p75NTR) in the most typical smoke-induced disease: Chronic Obstructive Pulmonary Disease (COPD) [14]. The gene discussed is NGFR; the disease is chronic obstructive pulmonary disease.