Since the bacterial component peptidoglycan directly stimulated breast cancer cells invasiveness and adhesiveness via cancer cell TLR2 activation, our results suggest breast cancer patient might be necessarily noticed mastectomy or mastitis-caused bacterial infection, especially induced by Gram-positive bacteria which usually enriched much more peptidoglycan, and indicate the significance for bacterial infection-associated cancer to receive antibiotic therapy. Here, TLR2 is linked to bacterial infectious disease.