MST1 expression. (A) MST1 transcript levels were quantified as the -fold difference of mRNA levels for MST1 normalized against the housekeeping gene ACTA1 (β-actin). Data are representative of 2 independent experiments performed in duplicate. (B) MST1 transcript levels were quantified as the -fold difference in mRNA levels for MST1 (normalized to ACTA1) in control sorted naive (CD4⁺ CD45RA⁺; CD8⁺ CD45RA⁺ CCR7⁺) and memory subpopulations of CD4 (CD4⁺ CD45RO⁺) and CD8 (CD8⁺ CD45RO⁺ CCR7⁻) T cells, as well as double-negative, double-positive, and single-positive thymocytes. Data are representative of 3 independent experiments performed in duplicate. (C) MST1 transcript levels in control and patient T cells. Data are representative of 5 independent experiments performed in duplicate. (D) A Western blot analysis of MST1 protein expression in lymphocytes from a healthy control, 2 heterozygous individuals (F2M, F1M), and 2 MST1-deficient patients with different homozygous nonsense mutations. Actin was used as the loading control. Data are representative of 5 independent experiments.