The oxidation step in peroxisomes is catalyzed by acyl-CoA oxidases (ACOX), and to date, there is very little functional understanding of ACOXs in cancer; likewise, the other enzymes of peroxisomal β-oxidation include D-bifunctional protein (DBP, encoded by HSD17B4), peroxisomal 3-ketoacyl-CoA thiolase (encoded by ACAA1), or sterol-carrier protein X (SCPx). The gene discussed is SCP2; the disease is cancer.