Fig. 5. Precocious involution in PKN1 transgenic mice. (A,B) Tissue sections were subjected to TUNEL assays at pregnancy day 18 (P18), lactation day one (L1), lactation day 2 (L2), and lactation day ten (L10). TUNEL-positive cells were identified by the green fluorescence and nuclei were stained with DAPI. Representative TUNEL-stained mammary gland sections from wild-type and transgenic mice on the second day of lactation are shown. Fraction of apoptotic cells at the analyzed developmental stages calculated from the ratio of TUNEL-positive epithelial cells to the total number of DAPI stained epithelial nuclei. Significance was determined using the Student's t-test (^*P<0.05); error bars depict the s.e.m. (C) Raw expression levels of the involution associated genes Tgfb3 and Igfbp5 on the first day of lactation in animals of the indicated genotype. Data were derived from microarray experiments involving triplicate samples for each group and tested for significance using the Student's t-test (^*P<0.05). Error bars represent the s.e.m. (D) Expression of Tgfb3 (arrow) on the second day of lactation in wild-type (wt) and transgenic (tg) animals as assessed by northern blot hybridization. The samples shown are representative of four animals analyzed in each group. Ethidium-bromide-stained ribosomal RNA is shown as a loading control in the lower panel.