An outstanding collection of both classic and cutting-edge techniques for the detection and measurement of mitogen-activated protein kinase (MAPK) signaling cascades. The protocols includes methods for the determination of the subcellular localization of these components, the structural and biophysical analysis of the components, and identification of novel components of known and unknown signaling cascades. Additional methods examine the upstream mechanisms of activation of MAPK cascades by various receptors, the mechanisms involved in the down regulation of the MAPK cascades, and identification of targets of the MAPK cascades. A number of techniques use inhibitors in research on MAPK and transgenic mice for studies of MAPK signaling. The techniques offer biochemists, cell biologists, physicians, and biotechnologists all the essential laboratory techniques needed in to conduct productive studies of MAPK signaling in health and disease, in measuring the influence of drugs, and in a broad range of experimental systems.