MDC1 and neoplasm: However, regarding tumor cells, the Oncomine and the Cancer Genome Atlas Program (TCGA) databases show that the expressions of DNA repair genes (e.g., BRCA1, BRCA2, ATM, PRKDC (gene name for DNA-PK), and MDC1) are upregulated in most tumor types, and that, 10–20% of tumor cells show mutations in these genes, which makes them resistant to DNA damage and radiotherapy-induced apoptosis.