Agarose gel showing α7 nicotinic acetylcholine receptor expression in A-549 adenocarcinoma, NCI-H727 carcinoid, and squamous cell lines NCI-H226, NCI-H520, and NCI-H2170. cDNA was amplified by PCR using the human α7 primers. 1) A549; 2) NCI-727; 3) NCI-H226; 4) NCI-H520; 5) NCI-H2170. For all gene expression experiments, negative control reactions were performed and found to be negative. The bands were consistent with the expected size, 335 bp. M-100 bp DNA ladder.