Abstract: Separation of macromolecules by one-dimensional or two-dimensional methods, such as gel electrophoresis, produces an array of macromolecules, which can be transferred to a support, thereby producing the same array as on the gel. In the case of one-dimensional gel electrophoresis, because of the regular spacing of the gel lanes and the predictable direction of migration of the macromolecules, the positions of the macromolecule spots or bands in the array can be predicted to be at least within the area of the support corresponding to the lanes of the gel. Where the molecular weight of a macromolecule of interest is known, molecular weight markers can be used to determine where the macromolecule band is on the support, even if the macromolecule is not stained in the gel or on the support.