NOS2 and hepatocellular carcinoma: While COX-2 impacts growth and progression of HCC and its inhibition suppressed HCC-associated angiogenesis in vitro and in vivo [45], iNOS is a key enzyme in generating nitric oxide, thus modulating tumorigenesis by regulating tumor cell proliferation, survival and migration, as well as angiogenesis, drug resistance and DNA repair [5,46].