Agarose gel showing α7 nicotinic acetylcholine receptor expression in normal small airway epithelial cells. cDNA was amplified by PCR using the human α7 and cyclophilin primers. 1) α7 primers; 2) cyclophilin primers. For all gene expression experiments, negative control reactions were performed and found to be negative. The bands were consistent with the expected sizes, 335 bp for the α7 primers and 216 bp for the cyclophilin primers. M-100 bp DNA ladder.