Formalin-fixed paraffin-embedded (FFPE) humanbreast cancer tissue sections were stained for multiplex MALDI-IHCwith six photocleavable mass-tagged (PC-MT) antibodies constitutinga breast cancer antibody panel (CD20, actin-αSM, HER2, CD68,vimentin, and panCK). This evidence concerns the gene ERBB2 and cancer.