CHRNA4 and small cell lung carcinoma: While the α7-nAChRs are overexpressed in small-cell lung carcinoma in smokers [118], in vitro experiments have suggested that the malignant growth can be ceased using snake neurotoxins (α-neurotoxins) or snail conotoxins (α-conotoxins), and these have been used for the isolation and biochemical characterization of nAChRs because they are competitive antagonists of the nAChR [119].