PTPRD and cancer: The PTPRD gene, specifically, is frequently inactivated by genetic (deletion, mutation, copy number loss) or epigenetic (hypermethylation) mechanisms in cancers, such as glioblastoma multiforme (GBM), colon cancer, breast cancer, neuroblastoma, lung cancer, and squamous cell carcinoma (SCC) [24,26,27,28,29,30,31,32].