Effects of M-CSF and IFN-γ on members of the MKP family. The expression of several MKPs was analyzed by rt-PCR. (A) Macrophages were stimulated with M-CSF for the indicated periods of time. Control cells were left untreated (0). (B) Macrophages were treated with M-CSF, IFN-γ, or both agents together for 30 minutes (for MKP-1), 2 hours (for MKP-2), or 2 to 6 hours (for MKP-4). (C) Macrophages were stimulated with IFN-γ for the indicated times and the expression of MKP-5 and -7 was analyzed. In all rt-PCR experiments, the expression values were normalized to the expression levels of the ribosomal gene L14. Each experiment was performed 3 times and a representative experiment from each one is shown here. Error bars indicate the variation between experiments.