Fig 3.

 Effect of celastrol on differentiated neuronal cells. Microscopic analysis using (A) phase contrast microscopy and (B) 4′,6-diamidino-2-phenylindole (DAPI)/propidium iodide (PI) staining on fixed cells showed that celastrol at 3 μM induced cell death in differentiated human (SH-SY5Y) and rodent (NG108-15) neurons. (C) A dose-response analysis demonstrated that the threshold at which neuronal viability was affected was 0.75 μM for both human neurons and rodent neurons in the differentiated state