THE C-TERMINAL SRC KINASE (CSK) IS WIDELY EXPRESSED, ACTIVE IN HT-29 CELLS THAT CONTAIN ACTIVATED SRC, AND ITS EXPRESSION IS DOWN-REGULATEDIN BUTYRATE-TREATED SW620 CELLS

Csk expression was examined in human glioma, breast and colon cell lin es, along with murine tissues. Relative to colon and glioma cell lines , Csk expression was highest in the breast cell lines. Relative to bra in tissue, expression was 100-fold higher in the heart, kidney, liver, lung and spleen. Subcellular fractionation and cellular immunostainin g indicated that it was localized in the cytosolic fraction. The expre ssion of Csk was downregulated upon chemical-induced differentiation o f SW620 human colon cells by treatment with sodium butyrate. Its expre ssion localization and activity relative to Src are discussed. (C) 199 6 Academic Press Limited