Figure 3. Spatial and temporal control of AR function with Cre recombinase.

(a) To achieve tissue-specific recombination, the Cre transgene is placed under the control of tissue specific regulatory elements. As Cre expression is spatially restricted, excision of the floxed AR allele occurs only in defined regions, leaving behind a single loxP site. (polyA: polyadenylation sequence.)

(b) To obtain spatial and temporal control of recombination, the CreER^T2 fusion protein is expressed under the control of tissue specific regulatory elements. In the absence of tamoxifen, CreER^T2 is sequestered in the cytoplasm and cannot act on floxed AR alleles in the nucleus. Binding of tamoxifen induces CreER^T2 translocation to the nucleus where CreER^T2 is now free to recombine the floxed AR allele.