Fig. 6. Reconstitution of the MRN complex and ATM activation in A-TLD(S) and NBS cells by ectopic expression of Mre11 and Nbs1, respectively. (A) Immunofluorescence images of the three components of the MRN complex in hTERT-immortalized A-TLD(S) fibroblasts following transduction with a control vector expressing GFP and a vector expressing wild-type Mre11 protein. In each panel the same field is shown in all photographs. (B) Immunoblotting analysis showing ATM activation in A-TLD(S) cells transduced with the control and Mre11 vectors. Note reconstitution of endogenous Rad50 and Nbs1 levels following ectopic expression of Mre11 and reconstitution of damage-induced ATM activation. (C) ATM activation in NBS cells reconstituted by ectopic expression of Nbs1 (Tauchi et al., 2001).