Among the other genes she says play a role in thoroughbred performance are peroxisome proliferator - activated receptor - γ coactivator - 1 alpha (PGC - 1α), which is involved in skeletal muscle adaptation to exercise; pyruvate dehydrogenase kinase, isozyme 4 (PDK4), involved in glucose regulation, expression of which increased almost fourfold after sprints; and
cytochrome c
oxidase subunit 4 isoform 2 (COX 4I2), involved in respiration.