Chromatin remodeling gene AT-rich interactive domain-containing protein 1A (ARID1A) encodes BAF250a protein,a noncatalytic subunit of the SWI/SNF chromatin-remodeling complex.Recently,ARID1A has emerged as a novel and bona fide tumor suppressor recurrently mutated at a rate ranging from ～10 to 50％ in a broad array of tumor types such as ovarian,liver,gastric and breast cancers.