To begin to understand the molecular mechanisms underlying the development of adenocarcinomas in NNK-exposed Gprc5a-knockout mice, we used microarray profiling, to compare and contrast the transcriptomes of MDA-F471 malignant cell line and normal lung epithelial cells isolated from NNK-exposed Gprc5a−/− mice and from normal tracheas of untreated Gprc5a−/− mice, respectively. This evidence concerns the gene GPRC5A and adenocarcinoma.