Methylation of the CHK2 gene promoter inhibited the CHK2 gene transcription and prevented from binding of the transcriptional factor: A: CHK2 promoter sequence -615/-411 was cloned into pGL3 luciferase reporter gene, and transfected into A549 cells, and the luciferase activity was assessed to determine the function of the CHK2 promoter sequence. WT-CHK2 represented a wild type sequence of the CHK2 promoter. M-WT-CHK2 represented in vitro methylated wild type CHK2 promoter by SSS I CpG DNA methylase. B: gel mobility shift assays using the wild type -615/-411 sequence of the CHK2 promoter as a probe. The unlabeled probe was 50X in excess, and the M-cold probe (50X in excess) was in vitro methylated wild type -615/-411 DNA as unlabeled competitor for binding.