In support of this hypothesis, quantitative RT-PCR analysis revealed that in contrast to the increase of c-Jun mRNA seen after treatment with EGF, which is known to elevate levels of c-Jun protein by working at the level of transcription, the increase in c-Jun protein seen in metastatic breast cancer cells was not accompanied by upregulation of c-Jun mRNA (Figure 3B). This evidence concerns the gene JUN and breast carcinoma.