Effect of lathyranes on NPC proliferation in vitro. Proliferation was tested in NPC cultures grown in the presence of bFGF. (A) Graph shows the effect of increasing concentrations of lathyranes (ELAC, EOF2, EOF3 and ELAF12‐2) on neurosphere area after 72 h of culture. A minimum of 540 neurospheres were measured per treatment. (B) Phase‐contrast microphotographs of neurospheres cultured for 72 h in the absence or presence of different lathyranes at a concentration of 5 μM. Scale bar indicates 200 μm. (C) Graph shows the effect of increasing concentrations of lathyranes on the number of neurospheres formed after 72 h of treatment. (D) PKC activity was measured in lysates obtained from cells that had been treated for 1 h with 5 μM prostratin, 5 μM ELAC or none, using a PKC activity assay kit. PKC activation induced by ELAC was similar to that induced by prostratin and was equivalent to the kinase activity observed in the positive control (consisting of 60 ng of purified active PKC). Results are the mean ± SEM of five independent experiments, and each individual experiment was performed in triplicates. *P < 0.05 when compared with control (untreated) cells in a Student's t‐test; a.u.: absorbance units.