Moreover, BRCA1 is a key component of a protein complex, termed BRCA1-associated genome surveillance complex (BASC) that contains tumor suppressors, DNA damage sensors and signal transducers, including MRN, the mismatch repair (MMR) proteins MLH1, MSH2, and MSH6, the Bloom syndrome helicase BLM, the ATM kinase, DNA replication factor C (RFC), and PCNA. This evidence concerns the gene BRCA1 and neoplasm.