Fig. 2.

pRb and p107 levels decrease during the death of cortical neurons evoked by camptothecin. A, Top, C, Top, Representative Western immunoblots of whole-cell extracts of cortical neurons treated with camptothecin for the indicated times and probed with antibodies for pRb (A) and p107 (C). Middle,Bottom, Cotreatment with flavopiridol (1 μm; middle) and BAF (100 μm;bottom) is indicated. Blots were stripped and reprobed for β-actin as a loading control. B, D, Densitometric analyses of Western immunoblots of cortical neurons treated with camptothecin alone or cotreated with flavopiridol or BAF and probed for pRb (B) or p107 (D). All data points are the mean ± SEM of data from three separate experiments and are expressed relative to the initial amount of protein at time 0.