RELN and Alzheimer disease: When disulfide bonds were not reduced Cont-Reelin failed to enter the SDS-PAGE resolving gel and most material remained at the top of the stacking gel; while Aβ-Reelin was resolved as monomer bands of 420, 310 and 180 kDa (Figure 4A), indicating that Reelin present in AD brain may not have capacity to form covalent dimers.