Figure 2. IS decreases the expression of Klotho in macrophages. THP-1 cells were exposed to PMA (160 nM) for 48 h and then incubated in PMA-free medium for 24 h followed by the indicated concentrations of IS (0, 0.25, 0.5, 1, or 2 mM) for 24 h. (A) RT-qPCR analysis of Klotho expression in cells. (B) Western blot analysis of Klotho protein expression. (C) Klotho expression was normalized to GAPDH. **P < 0.01 vs. IS-0 mM group.