Description_x000D_ Biochem/physiol Actions_x000D_ BRK is a member of the non-receptor tyrosine kinases (PTKs) that contains an amino terminal SH3 and SH2 domain as well as the catalytic domain. BRK expression is low or undetectable in normal mammary tissue and benign lesions. However, approximately two-thirds of breast tumors express appreciable levels and 27% of tumors over express BRK by fivefold or more._x000D_ Physical form_x000D_ Supplied in 50 mM Tris-HCl, pH 7.5, with 150 mM NaCl, 0.2 5mM DTT, 0.1 mM EGTA, 0.1 mM EDTA, 0.1 mM PMSF, and 25% glycerol._x000D_ Legal Information_x000D_ PRECISIO is a registered trademark of Sigma-Aldrich Co. LLC