·PEG-MGF, or PEGylated Mechano Growth Factor is a new and innovative form of MGF that outperforms natural MGF many times over. MGF is a splice variant of the IGF gene which increases stem cell count in the muscle and allows for muscle fibers to fuse and mature. This is a process required for growth of adult muscle. Natural MGF is made locally and does not travel into the bloodstream. Synthetic MGF is water based and when administered intramuscularly, travels into the bloodstream.