COUP-TFs regulate Gdnf, Eya1, Six2 and Wt1 expression in the metanephric mesenchyme in vitro. (A-F) Quantitative RT-PCR analysis of COUP-TFI (A), COUP-TFII (B), Gdnf (C), Eya1 (D), Six2 (E) and Wt1 (F) in rat metanephric mesenchyme-derived cells (RIMM-18), after knockdown of both COUP-TFI and COUP-TFII using specific siRNAs. All mRNA measurements were normalized to 18S rRNA. Error bars indicate s.d. **P<0.005.