Chronic treatment with ATRA induces UCP1 expression in differentiating mouse adipocytes. 3T3-L1 cells, WT MEFs, C3H10T½ cells and Rb−/− MEFs were treated with ATRA from day −2 to day 8 in the concentrations indicated. Total RNA and protein were harvested at day 8 and analyzed by RT-qPCR and immunoblotting, respectively. Relative mRNA expression levels of FABP4, UCP1 and RARβ were determined by normalization to expression levels of TATA-binding protein (TBP). (A) 3T3-L1 cells. (B) WT MEFs. (C) C3H10T½. (D) Rb−/− MEFs. (E) Protein levels of UCP1 with GAPDH used as a loading control. (A-D) Data represents mean + SEM (n = 3). *, p < 0.05 versus vehicle-treated cells.