ATRA enhances UCP1 expression independent of PGC-1α. Total RNA was harvested at day 8 (panel A) or at the indicated days (panel B) and analyzed by RT-qPCR. Relative mRNA expression levels of FABP4, UCP1 and RARβ were determined by normalization to TBP. (A) ATRA was supplemented to differentiating PGC-1α+/+ and PGC-1α−/− brown preadipocytes from day −2 to day 8 at the concentrations indicated. (B) ATRA (1 μM) was acutely supplemented to mature PGC-1α+/+ and PGC-1α−/− adipocytes from day 8 and harvested after 24 h. Data represents mean + SEM (n = 3). *, p < 0.05 versus vehicle-treated cells.