The Molecular Imaging Resource core will support the overall Program Project by housing resources and expertise necessary to prepare and introduce labeled proteins and proteins analogues into living cells, and then analyzing the spatial and kinetic distribution of these reagents and endogenous proteins as well as effects of these reagents on cell morphology, architecture and behavior. All projects of this program will make use of the activities of this core. The functions of this core include protein purification and derivitization with fluorescent tracers, introduction of proteins and expression vectors by microinjection, fluorescence recovery after photobleaching analysis, low light level time-lapse fluorescence imaging of labeled proteins and GFP-fusion proteins, immunolocalization of endogenous proteins and introduced reagents, computer-assisted analysis of cell shape and motility behavior, and 3-dimensional analysis and reconstruction of cell morphology and cytoskeletal architecture. Resources are available allowing these techniques to be applied to large cell populations or individual living cells. The specific aims of the Molecular Cytology Core are to: 1) develop and produce derivitized analogues of actin, 2) provide equipment, expertise and training for introducing macromolecules and expression vectors into living cells, and 3) provide technical assistance and training in computer assisted imaging techniques used to analyze static and dynamic distributions of cytoskeletal proteins in 2- and 3-dimensions.