PGR and breast cancer: Although TNBC is a type of breast cancer that lacks oestrogen receptor (ER), progesterone receptor (PR), and ERBB222 at the protein level, some populations within the tumour section expressed ERBB2 at the gene level, suggesting the intratumoural heterogeneity of the breast cancer type within a given tumour (Fig. 3d, Supplementary data 1).