Evidence of the role of NO• in carcinogenesis showed that both constitutive nitric oxide synthase (cNOS) and inducible nitric oxide synthase (iNOS) are detected in various human cancers.24,25 Previously, it is also reported that biopsy samples in a high-grade tumor of human breast cancer showed the presence of increased expression of iNOS.26 The gene discussed is NOS3; the disease is cancer.