Furthermore, the risk of developing mesothelioma has previously been associated with Heme oxygenase (HO)-1, a rate-limiting enzyme of heme degradation which plays a protective role against oxidative stress: Murakami and colleagues suggested that long (GT)n repeats in the HO-1 gene promoter are associated with a higher risk of malignant mesothelioma in the Japanese population [ 17]. This evidence concerns the gene HMOX1 and malignant mesothelioma.