ARID1A and breast cancer: Several genome-wide sequencing studies have uncovered frequent ARID1A mutations in a multitude of human cancers including subtypes of ovarian [8, 9], endometrial [10], uterine cancers [11], gastric carcinoma [12, 13], esophageal adenocarcinoma [14], breast cancer [15] and transitional cell carcinoma of the bladder [16].