Figure 2. The expression of KLF4 in wild-type and klotho (-/-) MEFs. qRT-PCR analysis of KLF4 and FOXO1 in wild-type and klotho (-/-) MEFs. Total RNA samples were prepared from wild-type and klotho (-/-) MEFs, followed by quantitative RT-PCR analysis to examine the expression levels of KLF4 (A) and FOXO1 (B). Transcript abundances were normalized to the GAPDH RNA level and are expressed as relative values. The mean ± S.D. of three independent experiments is shown. (C) Western blot analysis was performed to assess the KLF4 and FOXO1 protein levels. (D) Soluble klotho induced KLF4 transcriptional activation. Transient cotransfection with the pGL3-KLF4 reporter construct and pcDNA3-soluble klotho was performed in HEK239 cells, followed by the dual-luciferase assay as described in the Materials and Methods. The mean ± S.D. of three independent experiments is shown (*p < 0.05, **p < 0.01).