Immunohistochemical staining of PELP1 in TNBC. Positive immunostaining of PELP1 mainly distributed in nuclei of tumor cells, no cytoplasmic staining was found (a, b). Low grade lymph node stage TNBC showed weak PELP1 nuclear expression (a), High grade lymph node stage TNBC showed strong PELP1 nuclear expression (b). PELP1 nuclear staining was absent in negative control (c). Bar = 50 μm.