Tissue transgene expression. (A) Sketch showing the main features of the transgene construct. (B) Southern blot analysis showing the relative amounts of transgene DNA relative to WT RARα DNA in founder 17. Empty lanes correspond to mice that did not integrate the transgene. (C) RT-PCR analysis showing transgene expression in the spleen and mammary gland of a young, disease-free line 17 TG female (liver as negative control). Signal detected when the reverse-transcription step was omitted (-RT) is due to contaminating DNA (see Fig. 2 for DNAse I treatment control).