XBP1 and cancer: To evaluate whether Di Palma classification reflects the gene expression status, we assessed 14 cancer classification marker genes corresponding to immunostaining status: “HER2-positive Cancer”: ERBB2 and GRB7 (Growth factor receptor-bound protein 7), “Luminal-AR Cancer”: AR, ESR1 (Estrogen receptor 1), FOXA1 (Forkhead box A1), GATA3 (GATA binding protein 3), KRT8 (Keratin 8), KRT18 (Keratin 18), SLC39A6 (Solute carrier family 39), TFF3 (Trefoil factor 3), and XBP1 (X-box binding protein 1), and “Basal-Like Cancer”: EGFR, KRT5 (Keratin 5), and NOTCH1 (Notch 1).