ARID1A and endometrial cancer: Approximately ~ 6% of human cancers harbor inactivating mutations in ARID1A. Some of the cancer types showing the highest incidence of ARID1A inactivating mutations and loss of expression are clear cell ovarian cancer (~ 50%), endometrial cancers (~ 37%), gastric cancers (20–30%), bladder cancers (~ 20%), hepatocellular cancers (~ 14%), melanomas (~ 12%), colon cancers (~ 9%), and lung cancers (~ 8%) [21–23].