BCAR1 and breast cancer: In breast cancer cells, BCAR1 transcription is directly activated by the early growth response protein 1 (EGR1) in response to phorbol esters, but the presence of putative binding sites for additional transcription factors, such as NF-kB, p53 and HIF, in the promoter region [16] points to a more complex control of BCAR1 gene expression.