A specific protein precursor called pro-IGF-1Ec is cut by an enzyme named furin in human muscle and liver, resulting in a smaller fragment known as the Ec peptide. This indicates a biochemical process that modifies the protein after it is made.

Scientists found that a big protein called pro-IGF-1Ec gets cut by a special enzyme (furin) in human muscle and liver, releasing a smaller piece called the Ec peptide. This means the body naturally breaks down this protein in a way that matches what the claim says.