PTEN and breast cancer: In addition, several studies reported that reduced expression of CK8/18 can discriminate the basal tumors of BRCA1 mutation carriers from basal tumors of noncarriers [9],[10], whereas loss of phosphatase and tensin homolog (PTEN), together with triple-negative (TN; ER-, PR-, HER2-) status, was reported to improve the sensitivity of BRCA1 mutation prediction in a study of Asian breast cancer patients [11].