@entity842 (NO) and its metabolites are implicated in @entity105 and @entity3 . Both stimulatory and inhibitory effects of NO have been reported in relation to @entity0 and its role in the development of @entity5 and @entity3 remains uncertain. We have used the polyomavirus middle T antigen (PyV-mT) targeted to the @entity19 mammary gland and bred into an @entity13633 ( @entity13633 )-deficient C57Bl/6 strain to examine a role for @entity842 in modulating @entity5 that develop in the complex environment of the whole animal. The development of @entity1373 was delayed to the extent that the earliest palpable @entity5 arose 2-4 weeks later in PyV-mT/ @entity13633 (-/-) @entity19 compared with PyV-mT/ @entity13633 (+/+) @entity19 , identifying a role for @entity13633 in early events in mammary @entity5 formation. @entity5 that did develop in PyV-mT/ @entity13633 (-/-) @entity19 were characteristically well differentiated and had a cribriform pattern. Other @entity5 were @entity420 with uniform nuclear size. In contrast, @entity19 capable of @entity13633 activity typically developed solid @entity420 with a high mitotic index and pleomorphic nuclei. No significant effect of @entity13633 deficiency was found on vascular density in @entity1373 or @entity5 by examining @entity5231 -positive vessels. The infiltration of lesions by macrophages, cells capable of significant NO production, remained unchanged in PyV-mT/ @entity13633 (-/-) @entity19 . Metastatic potential was retained by PyV-mT-transformed epithelium in the absence of @entity13633 , indicating that NO production by @entity13633 is not essential for this process. These results indicate a role for @entity13633 in tumorigenesis, particularly in the regulation of early events.

XXXX latency is increased in @entity19 lacking the inducible @entity842 synthase.

@entity0 :: ('MESH:D001943', 'Disease') :: ['breast cancer'] @entity5 :: ('MESH:D009369', 'Disease') :: ['tumor', 'Tumors', 'tumors', 'malignancies'] @entity19 :: ('10090', 'Species') :: ['mice', 'mouse'] @entity1373 :: ('MESH:D006965', 'Disease') :: ['hyperplasias'] @entity842 :: ('MESH:D009569', 'Chemical') :: ['Nitric oxide', 'nitric oxide'] @entity13633 :: ('18126(Tax:10090)', 'Gene') :: ['inducible NO synthase', 'iNOS'] @entity3 :: ('MESH:D009362', 'Disease') :: ['metastasis'] @entity5231 :: ('18613(Tax:10090)', 'Gene') :: ['CD31'] @entity105 :: ('MESH:D063646', 'Disease') :: ['carcinogenesis'] @entity420 :: ('MESH:D000230', 'Disease') :: ['myoepithelial adenocarcinomas', 'nodular adenocarcinomas']
@entity5 :: (MESH:D009369,Disease) :: ['Mammary tumor']
