ERBB2 and cancer: In normal ducts, Her2/neu staining is negligible and p63 is exclusively localized to the myoepithelial cells (Fig. 4A, panels a-c), whereas microinvasive cancer cells adjacent to comedo-DCIS show positivity for both p63 and Her2/neu (Fig. 4A, panels f, g, j and k) or coexpression of p63/Her2/neu in malignant tumor cells (Fig. 4A, arrow in panel o).