The anaphase-promoting complex (APC) is a multisubunit E3 ubiquitin ligase that controls cell cycle transition in proliferating cells. Recent studies show that Cdh1-APC is active in postmitotic neurons, which regulates axonal growth and patterning, synaptic development and neuronal survival. However, the role of Cdh1-APC in neural stem cells differentiation remains unknown. Using quantitative reverse transcription-PCR, we observed that Cdh1 was expressed higher in neurons than in neural stem cells in vitro. Cdh1 was upregulated, whereas Id2 (one downstream substrate of Cdh1-APC) was downregulated when primary neural stem cells were induced to differentiate into neurons by all-trans retinoic acid. This observation suggests that Cdh1 is involved in the control of neural stem cells differentiated into neurons. NeuroReport 21:39-44 (C) 2010 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.