The nuclear hormone receptor peroxisome proliferator-activated γ (PPARγ) is expressed as two isoforms (PPARγ1 and γ2), and is an important modulator of monocyte gene regulation and function. TGF-β 1 is an essential and potent immune modulator and we therefore examined its effect on PPARγ expression in human THP-1 monocytes. TGF-β 1 strongly induced PPARγ2 mRNA and protein expression with a lesser effect on PPARγ1. Transcription from a PPARγ2 promoter/luciferase reporter vector was activated approximately 3-fold by TGF-β 1 . Mutation of two C/EBP elements within the PPARγ2 promoter reduced TGF-β 1 -induced transcription by approximately 65%. TGF-β 1 also induced the expression of three C/EBPisoforms (α, β, and δ). Induction of PPARγ1 and γ2 in monocytes by TGF-β 1 may contribute to the anti-inflammatory effects of this growth factor.