Fig. 1

Characterization of MMTV-Spy1 mice. a Schematic representation of the MMTV-Spy1 transgenic vector used in pronuclear injections for the generation of the MMTV-Spy1 mouse. b Spy1 expression in 8-week-old MMTV-Spy1 and control littermate (Cntl) inguinal mammary glands, where blue stain is haematoxylin and brown stain represents Spy1 expression. Representative images in left panels with quantification of Spy1 levels using ImageJ software analysis shown in the right panel. Scale bar = 100 μm. c Representative H&E stain of inguinal mammary glands from 6-week-old MMTV-Spy1 mice and control littermates (Cntl). Arrowheads point to areas with abnormal proliferative characteristics. Scale bar = 50 μm. d PCNA expression in MMTV-Spy1 and littermate controls via immunohistochemical analysis. Quantification of percentage of PCNA-positive mammary epithelial cells over five fields of view per sample (8 week Cntl n = 3, MMTV-Spy1 n = 4; 12 week Cntl n = 3, MMT-Spy1 n = 3; 16.5 day pregnant Cntl n = 1, MMTV-Spy1 n = 2; 4 day lactation Cntl n = 3, MMTV-Spy1 n = 2; 4 day involution Cntl n = 2, MMTV-Spy1 n = 2). e Cleaved caspase-3 (CC3) expression in MMTV-Spy1 and littermate controls via immunohistochemical analysis. Quantification of percentage of CC3-positive mammary epithelial cells over five fields of view per sample (8 week Cntl n = 3, MMTV-Spy1 n = 4; 12 week Cntl n = 3, MMT-Spy1 n = 3; 16.5 day pregnant Cntl n = 1, MMTV-Spy1 n = 2; 4 day lactation Cntl n = 3, MMTV-Spy1 n = 2; 4 day involution Cntl n = 2, MMTV-Spy1 n = 2). f Summary of proliferation and apoptosis data for developmental time course. Error bars reflect standard error (SE), Student’s T test *p < 0.05, **p < 0.01, ***p < 0.001. See also Additional file 1: Figure S1 and Additional file 2: Figure S2