Fig. 9. Upregulation of integrin 5 is found in regenerating fibers. (A) Immunoblot and graphical representation of integrin 5 expression in wild-type (normal), -sarcoglycan mutant (dsg^–/–), -sarcoglycan mutant (gsg^–/–) and dystrophin mutant (mdx) muscle protein. Integrin 5 is a fibronectin receptor in muscle and is upregulated in DGC mutant muscle. ß-actin labelling is shown in the lower panels as a loading control. (B) Immunoblot showing that integrin 5 is upregulated in double-mutant gxi and gsg^–/– mutant muscle compared to muscle from integrin 7 mutant (Itg7^–/–). ß-actin labelling is again shown in the lower panel as a loading control. (C) Immunostaining with an antibody to integrin 5 shows little to no increase in Itg7^–/– muscle compared to wild-type (WT) muscle. (D) Immunostaining shows that integrin 5 is found in regions of regeneration as the same fibers that are positive for integrin 5 also stain with embryonic myosin heavy chain (green). The increased fibrosis in gxi muscle also reacts with the integrin 5 antibodies consistent with its expression outside of muscle. Bar, 50 µm (C,D).