Fig. 1. Generation of MTA1-TG mice and expression of the MTA1 transgene. (A) The MMTV-MTA1 transgene. (B) Southern blot detection of the MTA1 transgene in the tail genomic DNA of transgenic (TG) and wild-type littermates of F1 from lines 30, 31, 32 and 33. (C) Representative PCR analysis of genomic DNA from potential founder mice. Lanes marked 10 and 1 show respective copy number equivalents of control MTA1 cDNA plasmid. (D) Time course of transgene expression in line 31 MTA1-TG mice analyzed by RT-PCR followed by Southern blotting. (E) Protein lysates from mammary gland of MTA1-TG and wild-type, virgin 12-week-old mice and pregnancy day 10, were immunoprecipitated with anti-T7 antibodies and western blotted with anti-T7 antibody. MCF7-MTA1 cell lysate was used as a positive control. (F) Immunohistochemical analysis of T7-MTA1 expression using anti-T7 antibodies in the mammary gland from 12-week-old virgin. A negative control without first antibody was shown. Note that the transgene is located in the nucleus of the luminal epithelial cells.