CD4 + T cells were centrifuged for 5 minutes at 500 g to remove the supernatant and then washed with ice-cold PBS. The PBS was then removed and the cells were lysed on ice for 30 minutes using freshly prepared RIPA-Buffer (ThermoFisher) containing Protease/Phosphatase inhibitor (ThermoFisher). Protein concentrations were determined using a BCA-Assay (ThermoFisher).