2.9 Reporter gene assay
A549 cells were transfected with NFAT-luciferase/Renilla plasmids by using polyjet transfection reagent (Signagen, SL100688). The transfected cells were pretreated w/wo lysine in a dose dependent manner for 2h, followed by 800 µM PQ stimulation for additional 24h. The amount of NFAT-luc or Renilla was measured by using the dual-luciferase Kit Assay Reporter System (Vazyme Biotech Co, DL101-01) and examined by using a luminometer (Varioskan Flash, Thermo Fisher, MA, USA). The data were present as the ratio of the NFAT-luc luminescence to Renilla luminescence.