POLG and breast carcinoma: Examination of non-neoplastic breast tissues from subjects with and without breast cancer revealed expression of POLG1 in < 10% of ductal epithelial cells (score +) in 2/13 cases, score ++ in 7/13 cases and highly expressed (score +++) in 4/13 cases (Table 1) (Fig 1D-III, IV and 1E).