Total RNA from E18.5 Pygo1/Pygo2 null and control kidneys (both represented in duplicate and distinct from the kidneys used for microrray analysis) was purified using a commercial kit (Absolutely RNA Microprep Kit; Stratagene, La Jolla, CA USA) including DNAse1 treatment. cDNA was generated using random hexamers according to conventional protocols (Invitrogen, Carlsbad, CA, USA). The following primers were generated to include the sequence obtained from the Illumina probe: Actb (TTGCTGACAGGATGCAGAAG, ACATCTGCTGGAAGGTGGAC); Aldh1a7 (CCAGAAAGTGGTGTTTTGCT, GAGTTACAGAGAGCTTGCACCTT); Col8a1 (GCAGACAGGCATCTTCACCT, TGTGTACATCATGGGCTCGT); Csrp1 (CAGCATAGCCCAGGGTAGAG, TGGGCAAGGTAGTGAAGGTT); Klk5 (GCAGCATTACACCCGTCATA, TTGCCTCCATCCATATCTCC); Picalm (GGGAGGGAACAGAAATCCTT, GCACCGATCAACAGTGCAG); Pygo2 (TTCTGGGAACTTGTGCACTG, AACTTCCTCCAGCCCATTTT); Ren2 (TTGTGAGCTGTAGCCAGGTG, TGTGCACAGCTTGTCTCTCC) and Tia1 (TGATTGAAGGGCTACTAGAGTGGT, AGCCCCAGAGGACAATTTTT) using Primer3 software [37]. Relative quantitative PCR was performed according to the conventional SYBR Green protocol (Stratagene) using a quantitative PCR system (Mx3000p; Stratagene). Dissociation curve and agarose-gel analysis of each primer set were used to insure specificity of the amplicon. All data were normalized to an internal housekeeping control (Actb) and analyzed using the 2(-Delta Delta C(T)) method [38].