ESR1 and breast neoplasm: Western blot of HER2, ER and PGR was performed, showing that they were representative of the human breast tumors with different levels of proteins of HER2 and PR (MCF7 as ER+/HER2−/PR+, BT474 as ER+/HER2+/PR+ and ZR751 as ER+/HER2+/PR-, supplementary file 2).