Figure 9.

Role of Numb isoforms in regulating the p53 response to genotoxic stress. (A) MCF-10A cells silenced for the indicated Numb isoforms were treated with increasing doses of cisplatin for 16 h and IB as indicated. p53-pSer15 represents the form of p53 activated by phosphorylation of Ser15, detected with a specific antibody. Molecular masses are given in kilodaltons. (B) MCF-10A cells silenced as shown on the right were left untreated (left) or treated with 12 µg/ml cisplatin for 15 h (middle) and then released in fresh medium for 24 h (right). IF with antiphosphorylated γ-H2AX was performed. The γ-H2AX foci per cell were counted in at least five random fields for each condition (from two independent experiments). In each field, the percentage of the cells with 0–1, 2–10, and >10 foci per nucleus was evaluated, and the mean of these percentages for each condition was reported in graph with its SD. *, P ≤ 0.01 compared with control in each group. (C) Representative panels of the MCF-10A cells used in B (and silenced as shown on the right) stained with antiphosphorylated γ-H2AX (red) and with DAPI (blue). Bar, 50 µM.