DLK1 and lung cancer: Among others, these include CASP9 and CDC42 (1p36), which have already been studied in neuroblastoma [27,28]; CACNA2D3 (3p21-p22), which was recently proposed as a tumor suppressor gene in lung cancer [29]; IGSF4 (11q23), which is a known tumor suppressor gene in several cancers; and DLK1 (14q).