Gfi-1 expression is down-regulated by TGF-β. CD4⁺ T cells from naive mice were activated under Th1, Th2, Th17, or iTreg conditions for (A) 4 d or (B) 24 h, or (C) under ThN (nonpolarization) conditions for 24 h followed by cytokine stimulation for 2 h. Cells were harvested and total RNAs were isolated. The relative expression levels of different genes normalized to GAPDH were assessed by real-time PCR after reverse transcription. Error bars represent means ± SD, and data are representative of two independent experiments.