CHRNA4 and lung cancer: It has been reported that both nicotine and 4-(Methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are able to induce lung cancer by binding to nAChR and activating PKC, Raf1, AKT, ERK1/2, and transcription factors such as Jun, Fos, and c-Myc [21], [42], [43], [44].