A: Effect of GST-irisin on the genes upstream of itself (PPARγ and FNDC5) in 3T3-L1 mature adipocytes. The mRNA expression was determined by qPCR. B: The mature adipocytes were cultured with various GST-irisin concentrations (0, 50, 100, and 200 nM) for 2 (a), 4 (b), 6 (c), and 8 (d) days. The irisin concentrations in the culture media in 3T3-L1 mature adipocytes were determined by ELISA. C: The GST-irisin concentration was 0 (white circles), 50 (white diamond), 100 (white triangle), and 200 (white squares) nM. D: The adipocytes were cultured with GST-irisin for 2 (a), 4 (b), 6 (c), and 8 (d) days. Values are expressed as the mean ± SD of 10 independent experiments. *P < 0.05 versus control; **P < 0.01 versus control.