Fig. S1. Exon9Δ encodes the mAb K56-386 Nesprin-2 Giant epitope. GFP-fusion proteins corresponding to various Nesprin-2 exons were constructed (indicated on the top of the panel). Ex9Δ is an Exon9 deletion equivalent to the following amino acid sequence: AKVRDALVWLTLQEKRFQKMLK. GFP-fusion constructs were transiently transfected into COS7 cells and whole-cell lysates were analyzed by SDS-PAGE and assayed by anti-GFP and anti-K56-386 immunoblotting. K56-386 detects bands representing GFP-fusions harboring Exon9-encoded peptides.

Fig. S2. Nesprin-2 codes for multiple and broadly expressed isoforms in WT and Nesprin-2ΔABD KO mice. (A) Western blot analysis of equal amounts of HaCaT (control) and various tissue homogenates using pAbK1 Nesprin-2-specific antibodies. Equal loading is indicated by the β-tubulin immunoblotting. (B) Table summarizing the pAbK1 immunoblotting data from 20 independently performed assays (using 12% and gradient gel SDS-PAGE) using the indicated WT and KO tissue lysates (four animals used for each strain). Due to Nesprin-2 isoform variability in the western blot analysis only the most consistent Nesprin-2 isoforms are indicated and the differences in WT and KO tissues are listed. The presence (indicated by the symbol: Œ) and the absence (indicated by the symbol: −) of a specific isoform in WT (wild-type) and KO tissue are indicated. Nesprin-2 isoforms, which exhibited an altered expression (reduction) in the KO tissue lysates are indicated with the symbol: ∼. Note that the absence of Nesprin-2 Giant has affected the expression of several Nesprin-2 isoforms in the examined tissues.

Fig. S3. Nesprin-2ΔABD is an aberrant giant Nesprin-2 isoform expressed in aged KO fibroblasts. Nesprin-2 pAbK1 immunoblot analysis of WT and various aged (>6 passages) KO fibroblast cell lysates. The KO cells implemented were isolated from different KO mice. Note the presence of giant pAbK1 reactive isoforms (arrowhead) in the KO lysates.

Fig. S4. Lamin A/C organization is perturbed in the KO fibroblasts. WT and KO cells were subjected to immunofluorescence using lamin A/C antibodies. Note the abnormal lamin A/C organization in the deformed NE area. Inset is a higher magnification of the outlined boxed area. Scale bar: 10 m. Confocal images are shown.