NID2 and breast cancer: Based on the results of MSRE-PCR, the genes were classified into two categories: genes with CpG islands nonmethylated in normal breast tissues but prone to abnormal hypermethylation in BC (ITGA1, ITGA4, ITGA7, ITGA9, NID1, and NID2), and genes with CpG islands found to be nonmethylated in all breast tissues, no matter normal or cancerous (ITGA2, ITGA3, ITGA6, ITGB1, and DAG1).