Fig. 1.

Effect of insulin on the extracellular levels of Aβ and sβAPPα in murine neuroblastoma cells (N2a) and primary rat cortical neuronal cultures. Cells were pulse-labeled for 20 min with [³⁵S]methionine and incubated in serum-free medium in the absence or presence of various concentrations of insulin for 4 hr. a, Representative autoradiographic analysis of extracellular Aβ (top) and sβAPPα (bottom) after incubation with or without 300 nm insulin. b, Extracellular levels of Aβ from N2a cells as a function of insulin concentration.c, Extracellular levels of sβAPPα from N2a cells as a function of insulin concentration. For b andc the data represent means ± SD;n = 3. d, e, IP–MS analysis of extracellular Aβ from primary neurons (d) and N2a cells (e) after incubation in the absence or presence of 1 μm insulin for 4 hr.