Pictured are mice injected with a fluorescently tagged peptide that binds to degraded collagen (seen as red) and a commercially available imaging agent that binds to the calcium in bones (seen as green). The mouse on the left was injected with both compounds, and the one in the right was injected only with the collagen mimetic peptide. (Areas where both compounds are present appear as yellow.) The purpose of these tests was to show that the peptides can target bone and cartilage of living animals by binding to degraded collagen. The peptide could someday deliver imaging agents and medications to combat various human disorders such as cancers, arthritis and fibrosis, which are associated with excess collagen degradation.