SATB1 is a nuclear protein which plays a crucial role in metastasis of breast cancer. It promotes tumor growth and metastasis by changing the expression of hundreds of genes, affecting cell adhesion, cell signaling, cell-cycle regulation, and other functions, including the epidermal growth factor gene Her2. SATB1 is not expressed in all cells. Only the metastatic cells express SATB1, and the most aggressive breast cancer cells show the highest levels of the protein. When SATB1 is detected in a breast tumor, the cancer is highly likely to progress or recur. Studies with human primary breast cancer tissue samples indicated that the highest levels of SATB1 were in samples from patients whose survival times had been shortest; patients whose tumor samples had no SATB1 expression generally had longer survival times. In addition, SATB1's ability to regulate gene expression was identified as critical to T-cell development. Studies revealed that SATB1 interacts with HDAC1 or PCAF, and is regulated by phosphorylation and cleaved by Caspase 6. The expression is high in Jurkat and low in HeLa cells.  Signosis offers SATB1 ELISA kit to facilitate the measurement of this important protein in cancer metastasis.