Transgenic PRL reduces the relative level of α-SMA: keratin 8 protein expression, and raises mammary tenascin C and maspin transcripts, without altering fibronectin 1. Protein homogenates and RNA from whole mammary glands of sham-treated 2 year old nontransgenic (FVB) and NRL-PRL nonparous females were examined for levels of α-SMA and keratin 8 protein by western analyses (A), and myoepithelial products by qRT-PCR (B, C, D), as described in the Materials and methods. A. Data are expressed as the ratio between α-SMA and keratin 8 staining (mean ± s.d., N=3). B, C, D. Data are expressed as mean ± s.e.m., N=5. Asterisk indicate a significant difference between genotypes by Student's t test (*, p<0.05; ***, p<0.0001).