Figure 2. The expression level of ATGs in young and old skeletal and cardiac muscle. (A-B) Immunoblot and densitometric analysis of ATG proteins in young and old skeletal muscle (A) and heart (B). (C) A diagram summarized the change of ATG proteins involved in the two ubiquitin-like conjugation systems in old muscle. Adapted under the terms of the Creative Commons Attribution License from , published by the BMC group. Copyright remains with the original authors. Values are means±SEM for 6 young and 5 old mice in each group. *P < 0.05. **P < 0.01.