GSK-3/β-catenin signaling downstream of anti-CD3 plus anti-4-1BB is dependent on PI3K-ERK pathway.

<p>(A–B) CD8⁺ T cells activated by anti-CD3 for 16 h were stimulated with 5 µg/ml of anti-4-1BB for the indicated times. Western blotting was performed with p-GSK-3β, p-ERK, β-catenin, and β-actin antibodies (A), and the relative expression levels were calculated by dividing the densitometry value of each protein by the value of β-actin (B). (C–D) The activated CD8⁺ T cells were pre-incubated with or without 10 µM LY294002 or 10 µM PD98509 and then stimulated with 5 µg/ml of anti-4-1BB or rat IgG for 1 day. Western blotting was performed with p-AKT, p-GSK-3β, p-ERK, and β-catenin antibodies (C) and the relative expression levels of each protein was determined (D). Results in B and D are mean ±SD of three separate experiments (*<i>p</i><0.05; **<i>p</i><0.01; ***<i>p</i><0.001).