The peroxisome proliferator-activated receptor (PPAR) gamma is a member of the nuclear hormone receptor family, which is predominantly expressed on adipocytes and considered to be involved in the process of adipogenesis. The new thiazolidinedione (TZD) compound, T-174, developed as an antidiabetic drug, stimulated the transcription of PPAR gamma and the adipocyte differentiation of 3T3-L1 cells. Interestingly, T-174 induced the interaction between PPAR gamma and CBP (cAMP response element binding protein (CREB) binding protein), a co-factor of various transcription regulators. CBP mRNA was expressed in both preadipocytes and adipocytes. These results suggest that CBP plays a role in the PPAR gamma-mediated signaling pathway activated by TZD, including adipogenesis.