IMMUNODETECTION OF ACTIVATED MITOGEN-ACTIVATED PROTEIN-KINASE IN VASCULAR TISSUES

Mitogen-activated protein kinase (MAPK) is a key modulator of cytoplas mic-nuclear signal transmission, and for this reason measurement of MA PK activity has become very popular. Monitoring of MAPK activity may b e particularly relevant to the cardiovascular system where it has alre ady been shown that the stimulation of cardiomyocytes and smooth muscl e cells by stretch and by growth factors activates MAPK. Since both gr owth factors and mechanical stress are causal agents for certain patho logies, enhanced MAPK activity may be a good predictor of disease prog ression. A variety of methods have been designed to measure the activa tion of this enzyme including an in vitro assay coupled to either gel electrophoresis or binding to P81 paper, an activity gel assay to dete ct p42/44 isoforms and, more recently, monitoring MAPK phosphorylation using immunoblot detection. The validity of the latter method is base d on the correlation between MAPK activity and the degree of phosphory lation. The antibodies have also been of use in the detection of MAPK translocation in cell monolayers. In this report, we discuss the advan tages and disadvantages of all MAPK detection methods and demonstrate an additional application for the MAPK antibodies using an in vitro re stenosis model. In addition, the utility of MAPK measurements to smoot h muscle pathophysiology and vascular injury (as a predictor of injury ) has been assessed.