Histologic and immunohistochemical examination of a true-cut biopsy revealed an invasive ductal adenocarcinoma, grade III differentiation, estrogen receptor (ER) strong nuclear positivity in 70% of cells, progesterone receptor (PR) nuclear positivity in less than 3%, HER2 strongly positive (+3), Ki-67 nuclear positivity in 40% of cells, and p53 nuclear positivity in 60% of cells according to the histopathology. The gene discussed is PGR; the disease is invasive ductal breast carcinoma.