Down-regulation of FOXO1, IL-7Rα, CCR7, and CD62L expression in MST1-deficient T cells. (A) Left: Western blot showing FOXO1 and MST1 protein level in whole-lymphocyte lysates from a healthy control, 2 heterozygous patients (patients F2M and F1M), and 2 MST1-deficient patients with different homozygous nonsense mutations (patients F1P1 and F2P3). Actin served as a loading control. Right: Abundance of FOXO1 relative to actin (signal intensity measurement). Results are presented as the FOXO1/actin ratio (in arbitrary units). Data are representative of 3 independent experiments. (B-C) IL-7Rα (CD127) and common cytokine receptor γ-chain (CD132) expression on CD3, CD8, CD4, CD4 CD45RA⁺, and CD4 CD45RO⁺ T cells from a control and an MST1-deficient patient (F2P2). Similar results were obtained for cells from F1P1. One of 6 experiments with similar results is shown (4 independent experiments for F2P2 and 2 for F1P1). (D-E) CCR7 and CD62L expression by freshly isolated control and MST1-deficient (F2P2) PBMCs. One of 6 experiments with similar results is shown (4 independent experiments for F2P2 and 2 for F1P1). (F) Quantitative PCR analysis of KLF2 mRNA expression. KLF2 transcript levels were quantified as the -fold difference normalized against ACTA1 (β-actin) mRNA levels in control (Ctr.) and MST1-deficient (F1P1 and F2P2) PBMCs.