Acute Rb removal results in neuronal apoptosis independent of classical E2f-regulated apoptotic genes. A, Cortical neurons were fixed at the indicated DIV and condensed nuclei were examined by DAPI staining (n = 3). B, Western blot analysis of total protein extracted from control and Rb-deficient cortical neurons at the indicated DIV. C, Cortical neurons were infected with the indicated constructs, and condensed nuclei were examined by DAPI staining at 8 DIV (n = 3). D, Western blots on total protein extracted at 6 DIV. E, qRT-PCR on RNA extracted at 6 DIV. RNA levels were normalized to GAPDH (n = 3). *p < 0.05,***p < 0.001. Error bars indicate SEM.