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. 2006 Dec 1;20(23):3238–3243. doi: 10.1101/gad.1496606

Figure 4.

Figure 4.

MDC1 knockdown does not affect checkpoint signaling in response to telomere dysfunction. (A) Immunoblot detection of ATM-S1981-P and Chk2-P after telomere deprotection. Whole-cell lysates of TRF2F/− lig4−/− p53−/− MEFs expressing control luciferase or MDC1-specific shRNAs, sh4 and sh5, were analyzed 72 h after mock or Cre infection. TRF2 and Rap1 immunoblots confirm efficient TRF2 deletion. (B) Detection of up-regulation of p53 and p21 in primary cells. Vector or MDC1 shRNA-treated IMR90 cells were harvested for immunoblot analysis 48 h post-infection with TRF2-DN (AdDN), the β-gal adenovirus control (AdβG), or 1 h post-irradiation with 5 Gy (IR). The MDC1 immunoblot confirmed knockdown of MDC1 by two independent shRNAs; TRF2-DN expression is detected with a myc antibody. (C) Microscopic images of IMR90 cells, expressing vector or MDC1 shRNA, sh1, infected with empty vector control or TRF2-DN retrovirus stained for SA-β-galactosidase activity at 12 d after infection. (D) Lack of effect of MDC1 shRNA on proliferation of MEFs. Growth curve of TRF2F/− p53−/− MEFs after Cre infection. Inset table represents percent of BrdU-positive cells 72 h after mock or Cre infection.