IGF1 and chronic obstructive pulmonary disease: In COPD muscle, impaired anabolic signaling (reduced insulin-like growth factor-1 [IGF-1]/Akt [proteinkinase B]/mTOR [mechanistic target of rapamycin] activity together with overactive transforming growth factor-β [TGF-β] family brakes [myostatin/activin]) suppresses protein synthesis and myogenesis [15,16,85].