Two-color PALM can be used to address fundamental questions on molecular organization. (a) Adhesion proteins paxilin (green) and zyxin (red) are shown by two-color PALM to adopt different spatial distributions even though they appear colocalized in (b) diffraction limited microscopy. (c) A differential interference contrast image of the image shown in (b).51 Reproduced with permission from Hari Shroff, Catherine G. Galbraith, James A. Galbraith, Helen White, Jennifer Gillette, Scott Olenych, Michael W. Davidson, and Eric Betzig. “Dual-color superresolution imaging of genetically expressed probes within individual adhesion complexes.” Proceedings of the National Academy of Sciences 104, no. 51 (Dec 18, 2007): 20308−20313. Copyright (2007), National Academy of Sciences, U. S. A.