Heat shock modulates cellular pro-inflammatory responses and we have been interested in elucidating the mechanisms that govern this modulation. The dual specific phosphatase, MKP-1, is an important modulator of cellular inflammatory responses and we recently reported that heat shock increases expression of MKP-1. Herein we sought to elucidate the mechanisms by which heat shock modulates MKP-1 gene expression. Subjecting RAW 264.7 macrophages to heat shock increased MKP-1 gene expression in a time-dependent manner. Transfection with a wild-type murine MKP-1 promoter luciferase reporter plasmid demonstrated that heat shock activates the MKP-1 promoter. When the reporter plasmid was transfected into heat shock factor-1 (HSF-1) null fibroblasts, the MKP-1 promoter was activated in response to heat shock in a similar manner to that of wild-type fibroblasts with intact HSF-1. Site-directed mutagenesis of two potential heat shock elements in the MKP-1 promoter demonstrated that both sites are required for basal promoter activity. mRNA stability assays demonstrated that heat shock increases MKP-1 mRNA stability compared to cells maintained at 37° C. Inhibition of p38 MAP kinase activity inhibited heat shock-mediated expression of MKP-1. These data demonstrate that heat shock regulates MKP-1 gene expression at both the transcriptional and post-transcriptional levels. Transcriptional mechanisms are HSF-1-independent, but are dependent on putative heat shock elements in the MKP-1 promoter. Post-transcriptional mechanisms involve increased stability of MKP-1 mRNA that is partially dependent on p38 MAP kinase activity. These data demonstrate another potential mechanism by which heat shock can modulate inflammation-related signal transduction.