Plasmid HRE–luciferase assay

Cells in 24‐well plates were transfected with 2 μg/mL HRE reporter plasmid (Addgene, Cambridge, MA, USA) and 0.02 μg/mL phRL‐CMV Renilla luciferase plasmid (used as control for normalizing transfection efficiencies) using PolyFect (Qiagen). After transfection, cells were incubated with or without IL‐6. Twenty‐four hours later, luciferase activities were measured using the Dual‐Luciferase Reporter Assay System (Promega, Madison, WI, USA) according to the manufacturer's instructions. Luciferase activity was measured using the GloMax 20/20 luminometer (Promega). For data analysis, the experimental reporter was normalized to the level of constitutive reporter to adjust for the differences in transfection efficiency.