LPS causes phosphorylation of STAT3, translocation of NFκB, and invasion of CD11b+leucocytes into the mammary alveolar lumen. Mammary glands non-treated (0 h) and at 3, 6, and 12 h after LPS injection were immunostained with anti-phosphorylated STAT3, anti-pan-keratin, anti-NFκB, and anti-CD11b antibodies. (A) Immunostained images of phosphorylated STAT3 (green) were merged with images of pan-keratin (red) as a marker of epithelial cells. (B) Immunostained images of NFκB (green) were merged with images of CD11b (red) as a marker of leucocytes containing neutrophils. Blue represents nuclear staining with DAPI. Arrowheads indicate the localization of NFκB in nuclei of AEC. Scale bars: 20 μm.