Stimulation of cells using EGF-coated magnetic beads.

The ability to determine the spatial localization of signals can assist in defining the regulation of specific signaling pathways within the cell. Localized application of a stimulus, followed by imaging of various proteins or their phosphorylated products, allows visualization of the propagation scales of responses to the stimulus. To obtain a localized stimulus of epidermal growth factor (EGF), we bound the ligand to magnetic beads, which could be rapidly pulled onto cell surfaces by a magnet. This method allows the spatial analysis of EGF-induced signaling pathways.