Fig. 1. Transgene and its expression in the mouse mammary gland. (A) The ß-catenin construct used for expression under the control of the K5 promoter in the basal mammary epithelial cells. (B) RT-PCR analysis of transgene expression in 7.5-day-pregnant mouse mammary glands. 18S RNA was used as a normalization control for RT-PCR. (C) Western blotting analysis of 7.5-day-pregnant wild-type and transgenic mouse mammary gland protein extracts performed with anti-HA-tag antibody. ß-Actin served as loading control. (D) Double immunofluorescence labeling showing transgene expression in a mammary duct of K5-N57-ßcat mouse. The transgene product detected with anti-HA-tag antibody is found in the basal cell layer of the mammary epithelium in correlation with the K5 expression, whereas the luminal epithelial cell layer is not labeled (arrows). DAPI was used to stain the nuclei. L, lumen. Scale bar: 10 µm.