Effects of dexamethasone and MAO B inhibitors on cell proliferation rates. A. Dexamethasone lowers the proliferation rates of both SH-SY5Y and 1242-MG cells. Cells were treated with dexamethasone (0 or 10 µM) for 96 h, and the proliferation rates were determined by MTT assay. *P<0.05 compared with control cells (without treatment). B. The MAO B inhibitors, rasagiline, selegiline, and 1-R-aminoidan (rasagiline’s metabolite) increase the proliferation rates in both SH-SY5Y and 1242-MG. Cells were treated with dexamethasone (0 or 10 µM) and/or 0.25 nM rasagiline or selegiline or 1 µM 1-R-aminoindan for 96 h, and the proliferation rates were determined by MTT assay. *P<0.05 and **P<0.02 compared to cells treated with dexamethasone alone