JUN and breast cancer: These results supported that deletion of wt-p53 promoted degradation of CXCR4, at least partially, by modulating the expression of AIP4. Interestingly, Mehta and colleagues have revealed that in breast cancer cells, wt-p53 could indirectly and negatively regulate the expression of CXCR4 through inducing the binding of the transcription factors ATF-1 and c-Jun to a cyclic AMP/AP-1 response like element in the CXCR4 promoter (Mehta et al., 2007).