For breast cancer, differences in protein profiles are found between classes 0 and 6 (sdis = − 1.85; p = 0.0; srand = 1.8e−5; characteristic protein profiles increased in class 0: ER-alpha, PR, GATA3, Bcl-2, Caveolin-1, AR, and INPP4B—for class 6: ASNS, Caspase-7_cleavedD198, and Cyclin_B1) and between class 0 and class 4 (sdis = − 1.64; p = 0.0; srand = − 7.6e−5; characteristic proteins increased in class 0: ER-alpha, PR, GATA3, Bcl-2, and INPP4B—increased in class 4: Cyclin_B1 and ASNS). This evidence concerns the gene ESR1 and breast cancer.