STAT3 luciferase reporter assay

Luciferase assays were used to confirm p-STAT3 transactivation in the H292 cells, which were seeded on a 24-well plate at a density 1 × 10⁵ cells per well 24 h prior to transfection. The STAT3-TA-luc vector (kindly provided by HM Shen at the National University of Singapore) was mixed with Renilla luciferase vector (Promega, Fitchburg, WI, USA) at a 7:1 ratio. Lipofectamine 2000 (Life Technologies) was used according to the manufacturer's protocol, and physalin A was added 24 h post-transfection for an additional 8 h. Cells were harvested, and luciferase activities were determined using the Dual-Luciferase reporter assay (Promega).