ESR1 and neoplasm: Similar significant signaling alternations including increased activation of HER2, HER3, SRC, AKT, and ERK and increased EGFR, SRC, and ER protein levels were observed following tamoxifen treatment in E2-E10-expressing T47D xenograft tumors, and to a lesser degree in E2-E7-expressing tumors (Fig. 3c, Additional file 4: Fig. S4), consistent with their tumor growth curves shown in Fig. 1a, b.