Fig. 9.

Maintenance of cell cycle block in primary neurons. Microarray analysis revealed changes in genes expression of molecules involved in cell cycle that were either downregulated (italics) or upregulated (underlined). Downregulated molecules include factors involved in promoting cell cycle, such as cyclins and CDKs, and upregulated molecules were mostly antiproliferative, such as Rb and p21. The pattern of change in the level of these molecules can maintain a block in cell cycle at two levels: G₁/S block and G₂/M block, which will keep the cell nondividing, despite the presence of stimulatory growth factors.