β-Amyloid (31-35) is a functional cytotoxic domain of Aβ peptide. β-Amyloid (31-35) increases the phosphorylation of biotinylated Aβ(1-40), enhances CDK-1 activity, and also inhibits binding of Aβ to cyclin B1. β-Amyloid (31-35) is cytotoxic, and such an effect can be inhibited by olomoucine in differentiated human teratocarcinoma cell line, Ntera 2/cl-D1 (NT-2) neurons. β-Amyloid Aggregation Guidelines (Following is our recommended protocol. This protocol only provides a guideline, and should be modified according to your specific needs). 1. Solid Aβ peptide was dissolved in cold hexafluoro-2-propanol (HFIP). The peptide was incubated at room temperature for at least 1h to establish monomerization and randomization of structure. 2. The HFIP was removed by evaporation, and the resulting peptide was stored as a film at -20 or -80 °C. 3. The resulting film was dissolved in anhydrous DMSO at 5 mM and then diluted into the appropriate concentration and buffer (serum- and phenol red-free culture medium) with vortexing. 4. Next, the solution was age 48h at 4-8 °C. The sample was then centrifuged at 14000g for 10 min at 4-8 °C; the soluble oligomers were in the supernatant. The supernatant was diluted 10-200-fold for experiments. Methods vary depends on the downstream applications.