The role of calpain and protein kinase C in activation of human neutrophils.

These and earlier findings suggest that certain neutrophil biochemical responses induced by external stimuli are mediated by the reorganization of the cytoskeletal-membrane interactions. This rearrangement of the intracellular architecture appears to result from a coordinated and integrated operation of two enzymes, namely PKC and calpain. This conclusion is schematically represented in a comprehensive model, discussed in the introduction and derived from a number of experimental observations. In focusing the importance of cytoskeletal reorganization, signal-directed proteolysis, induced by specific PKC-mediated phosphorylation, appears to play a fundamental role in cell functions such as positioning and fusion of organelles with plasma membranes and possibly locomotion and transport.