The distribution of immunopositive reactions in atypical cells of triple-negative breast cancer among patients, depending on the marker, was as follows: NIS-positive reactions were found in 112 women (69.5%); Mammaglobin in 50 (31.0%); and GATA-3 in 102 (63.3%). The gene discussed is GATA3; the disease is triple-negative breast carcinoma.