The Jak2 noncanonical function is sufficient for IFN-γ–responsive target gene expression. MEFs from Jak2^+/+, Jak2^FF/FF and Jak2^−/− mice were stimulated with IFN-γ for the indicated time. Subsequently, RNA was prepared and analyzed by quantitative reverse-transcription PCR for expression of IDO, CXCL9, GBP2, CXCL11, IFR1, and iNOS. Each data point represents the arithmetic means of 2 independent experiments of triplicate samples (n = 2 × 3). ***P < .001, **P < .01. The standard deviation is indicated for each data point.