iNOS expression inhibits cell proliferation and protein biosynthesis. (A) NO production. Stable A2008 transfectants with pCMV-IFN-γ were co-cultured with RAW264.7 in the presence or absence of NMA for 24 hr. Nitrite levels in the culture media were determined by the Griess reaction. (B) Cell proliferation. Co-cultured cells were labeled with 3H-thymidine for 18 hr for determination of proliferation rates. (C) Protein synthesis. After coculture for 16 hr, cells were incubated with 35S-methionine for 4 hr. Incorporation of 35S-methionine into protein was measured using a scintillation counter after TCA precipitation. All data are expressed as mean ± SD of three independent experiments, each performed in duplicate.