An Electrophoretic Characterization of the Glucocorticoid Response of the Fu5‐5 Rat Hepatoma Cell Line

In this study we have further characterized the response of liver‐derived cells to glucocorticoid treatment using the rat hepatoma, Fu5‐5. Using two‐dimensional electrophoresis we have examined changes in the synthetic rates of cytosol proteins following glucocorticoid administration by using [³⁵S]methionine. We have also demonstrated changes in the incorporation of ³²P by several cytosol proteins after hormone treatment. One of these changes occurs within 1 h of hormone treatment. We were unable to detect any changes in the nuclear protein content of Fu5‐5 cells after glucorticoid treatment. We then compared the glucocorticoid‐regulated changes in cytosol protein synthesis in Fu5‐5 cells with those of the H35 rat hepatoma, monolayer cultures of rat hepatocytes and the response of rat liver in vivo. This examination revealed that although nearly all of the eighteen hormonally responsive proteins appeared to be present in all of the cell types, only three were responsive to glucocorticoid in more than one system. Moreover, the response patterns were often reversed in different cell types, the same protein being induced in one cell type and repressed in another.