A-D, SGZ-aNPCs were treated with 0, 0.1, 0.2, 0.5, 1, or 2 μM lead for 48 h. Representative BrdU and Hoechst co-staining from (A) untreated, (B) 0.2 μM, and (C) 0.5 μM lead-treated SGZ-aNPCs, and quantification of (D) the percent BrdU+ cells. BrdU: a marker for cells in S phase of the cell cycle. Scale bars: 50 μm. n = 2 independent, experiments for a total of 8 coverslips per data point. Data represent mean ± SEM., n.s. not significant, * p < 0.05; ** p < 0.01.