Hornerin expression throughout the stages of mammary development. (A) Representative images of mammary glands isolated from the indicated stages of development that were subjected to immunohistochemical analysis using a hornerin-specific antibody or corresponding negative control. (B) Data represent the mean +/− SD of a minimum of three glands quantitated using Image J64. *P < 0.05 compared to nulliparous and pregnant glands. (C) Data represent the mean +/− SD of number of hornerin positive macrophages counted per 40x field; a minimum of three glands was counted at each developmental stage and three fields were counted per slide. * *P < 0.05 compared to nulliparous glands. (D) Representative images of immune cells in mammary glands that were subjected to immunohistochemical analysis using a hornerin-specific antibody and the corresponding PCR analysis of hornerin in human monocytes/macrophages isolated from peripheral blood; cells were treated +/− 20 ng/ml of LPS/IFNγ for five days. N = nulliparous week 5, Pg = pregnancy day 9, L D1 = lactation day 1, L D15 = lactation day 15, I D1 = involution day 1, I D7 = involution day 7. Yellow bar = 200 μm, Red bar = 50 μm.