By an approach using Sequenom MassARRAY platform for quantitative detection of methylated DNAs, we found that the global methylation level of target CpG islands of TAP1, LMP7 and ERp57 genes was significantly higher in genomic DNA of CSCC than in either CIN or normal controls (P<0.05), but no difference was found for TAP2 and tapasin (Table 2). The gene discussed is PDIA3; the disease is cervical squamous intraepithelial neoplasia.