DNA copy number, methylation level and gene expression of GPX3 in gastric cancer cell lines.

Copy number of the GPX3 gene was determined using qPCR and normalized to 10 normal blood DNA samples as described in the Methods section. The real copy number of each sample equals to the above copy number ratio times 2. DNA methylation levels were determined using Pyrosequencing and are shown as an average level of the 8 CpG sites in the GPX3 promoter region. GPX3 mRNA expression fold was determined using real-time RT-PCR and normalized to the average value of normal gastric samples as described in the Methods section.