NOS2 and colon carcinoma: For instance, more than 90% of oestrogen receptor negative breast cancer patients die with moderate to high iNOS expression [7], and iNOS is found in approximately 80–100% of prostate cancer specimens [8], 60% of advanced melanoma patients [9], 60% of human colon adenomas and 20–25% of colon carcinomas [10], in contrast to normal tissue, in which low levels of iNOS are observed.