Fig. 8. Pre-treatment with geldanamycin or dominant-negative p50cdc37 abrogates the induction of c–myc by IFN–γ. (A) Stat1-null MEFs were serum-starved and either untreated or pre-treated with geldanamycin (GA, 2 μg/ml) for 5 h. The cells were unstimulated or stimulated with IFN–γ, IFN–β or PDGF for 30 min. c–myc and GAPDH mRNA levels were determined by Northern blot analysis. (B) Stat1-null MEFs were transiently transfected with vector alone or vector encoding dominant-negative p50cdc37. The transfected cells were serum-starved for 24 h and either unstimulated or stimulated with IFN–γ for 30 min. c–myc and GAPDH RNA levels were determined as above.