ERBB2 and breast cancer: On IHC evaluation, tumor cells were strongly positive for epithelial markers CAM5.2 and keratin AE1/AE3; weakly positive for BC marker TRPS1; and negative for BC markers GATA3, ER, PR, and HER2-neu; squamous cell carcinoma markers p63 and CK5; and melanoma marker SOX10 (Figs 1B-1D).