ESR1 and carcinoma: One Pik3caH1047R;Trp53R270H;MMTV-Cre poorly differentiated carcinoma showed a few Pgr-positive cells and was Esr negative, and another Pik3caH1047R;Trp53R270H;MMTV-Cre sarcomatoid adenocarcinoma showed only a few Esr-positive cells (Additional file 1: Figure S6C and 6E).