AIDS-KS cells contain NOS 2 protein and demonstrate tyrosine nitration of MnSOD. Western blot analyses (A) showed that regardless of culture conditions, i.e. log growth in complete medium (lanes 1 and 4), sera deprivation (lanes 2 and 5) or TNF-α challenge (lanes 3 and 6), cultured AIDS-KS cells contain detectable protein levels of the high output NOS isoform, NOS 2. Immunoprecipitation-immunoblotting studies showed that AIDS-KS cells demonstrated nitration of their MnSOD tyrosine residues during all culture conditions [log growth (lanes 1 and 4), sera deprived control (lanes 2 and 5), and sera deprived + TNF-α challenge (lanes 3 and 6), B]. Notably, TNF-α challenge markedly increased the extent of MnSOD tyrosine nitration.