Comparison of expression levels of α7 nicotinic acetylcholine receptor between a representative SCLC cell line (NCI-H82), and SAE cells by a nuclease protection assay. A riboprobe transcribed from the human α7 PCR primer was used to compare expression levels in the two cell systems. 1) NCI-H82; 2) SAEC; 3) Yeast RNA. The protected fragments were consistent with the expected sizes, 335 bp for the α7 primers and 115 bp for the 28S ribosomal RNA control primers. The molecular weight markers are indicated by the numbers on the left side of the figure.