TWEAK-neutralizing antibody rescues denervation-induced muscle loss in mice. 2-mo-old C57BL/6 mice were denervated for 2 d, followed by intraperitoneal injections of 200 µg/mouse of either rat IgG1 or anti-TWEAK every third day for 12 d (n = 4 in each group). (A) Representative photomicrographs of H&E-stained sections of control and denervated TA muscle of isotype and anti-TWEAK–treated mice. (B) Quantification of fiber CSA in TA muscle sections of isotype and anti-TWEAK–treated mice. *, P < 0.01 (values significantly different from denervated TA muscle of IgG1-treated mice). (C) H&E-stained sections of control and denervated soleus muscle of mice treated with isotype or anti-TWEAK. (D) Quantification of fiber CSA in soleus muscle sections. ^#, P < 0.05 (values significantly different from denervated soleus muscle of IgG1-treated mice). (B and D) Error bars represent the SD. ITCT, isotype control. Bars, 20 µm.