Figure 5. Upon aging, the tibialis anterior and soleus undergo similar changes in mitochondrial biogenesis, fission/fusion, disposal and autophagy marker expression. Markers of mitochondrial biogenesis, fission/fusion, disposal and autophagy were evaluated in tibialis anterior (A, C) and soleus (B, D) muscles isolated from young (3 mo) and old (29 mo) mice. A-B) Representative OXPHOS subunits, PGC-1α, PGC-1β, Mfn2, short (S)- and long (L)-OPA1, LC3-II/I, and APG5 in whole muscle lysates were evaluated by Western blotting and normalized to Ponceau-stained total protein (see