Proliferation of neural stem cells is greatly enhanced by TNF treatment. (A) Incorporation of bromodeoxyuridin (BrdU) into newly-synthesized DNA was determined using BrdU-dependent fluorescence enhancement of TO-PRO-3 (red). Cultures (+TNF) were treated with 10 ng/ml TNF for two days. Scale bar depicts 100 μm. Note the larger neurospheres after TNF treatment. (B) Quantification of BrdU incorporation is shown as mean ± SEM of at least four independent determinations (***P < 0.001). (C) Total cell number determination confirms higher proliferation of TNF-treated cells. Note that pharmacological blockade of the NF-κB pathway by PDTC counteracts TNF-induced proliferation (***P < 0.001).