The rationale for the use of ACS to treat equine tendinopathies is based on several findings: 1) It was shown in an experimental study that the expression of IL-1β (and matrix metalloproteinase-13) is upregulated following overstrain injury of rat tendons, demonstrating that these molecules are important mediators in the pathogenesis of tendinopathy [15, 20]. The gene discussed is IL1B; the disease is disease of the tendon.