Sodium iodate

After washing in PBS, the dissected mammary glands and tumors were fixed in 4% paraformaldehyde–PBS overnight and for 2 days, respectively. After washing in PBS, samples were dehydrated gradually from 70% ethanol to 100% ethanol and then from 50% xylene in ethanol to 100% xylene, following paraffin replacement using a Leica ASP300 fully automatic closed tissue processor and paraffin-embedding using a Leica EG1160. The paraffin-embedded tissues were then cut into 5-μm thick sections using a Leica SM200R sliding microtome. The sections were gradually deparaffinized in xylene and then with ethanol, gradually decreasing from 100% to 50% ethanol, and washed with distilled H₂O, and then stained in hematoxylin solution (0.25% hematoxylin (Nacalai Tesque), 0.05% sodium iodate (Nacalai Tesque), 12.5% potassium alum (Wako), and 0.25% citric acid (Wako)) for 10 min. After washing in distilled H₂O, sections were blued in 0.1% saturated lithium carbonate at 37 °C for 5 min and then washed in distilled H₂O and stained in eosin solution (1% eosin (Wako) and 0.02% glacial acetic acid) for 10 min. After washing in 90% and 100% ethanol, sections were soaked in xylene for 5 min and then mounted in MGK-S (Matsunami).