Figure 4.

Activation of ERβ, not ERα, promotes the mitotic markers, CDK1/cdc2 and PCNA expression in hNPCs. Cultures of hNPCs were incubated in the presence or absence of E₂, PPT (an ERα-selective ligand, 0.5 nm), or DPN (an ERβ-selective ligand, 0.3 nm) for 24 h. Western blot analysis was conducted to determine protein expression of CDK1/cdc2/p34 (A) and PCNA (B). E₂ and ERβ-selective agonist, DPN, significantly increased CDK1 and PCNA expression, whereas the ERα-specific ligand, PPT, did not. Western blot data, normalized by β-actin, are presented as mean ± sem from three independent experiments. *, P < 0.05.