Fig. 1. c–myc mRNA expression in response to IFN–γ in Stat1-null and wild-type MEFs. (A) Subconfluent, serum-starved MEFs were either untreated or treated with 1000 IU/ml of murine IFN–γ for 15 or 30 min. c–myc and GAPDH mRNA levels were analyzed by Northern blotting. (B) Stat1-null cells were treated with murine IFN–γ (1000 IU/ml). c–myc and GAPDH mRNA levels were determined as above. (C) Wild-type cells were treated with murine IFN–γ (1000 IU/ml). c–myc and GAPDH mRNA levels were determined as above. (D) Subconfluent, serum-starved fibroblasts were either untreated or treated with 1000 IU/ml of murine IFN–γ for 30 min. Northern blot analyses were conducted with the probes indicated.