Activation of a human ST2-dependent NF-kappaB pathway. HEK-293 cells were transiently co-transfected with 500 ng of human ST2-containing vector (or empty vector as a negative control), a vector containing NF-kappaB-driven firefly luciferase, and a vector containing Renilla luciferase as a internal control in a 12-well plate. 40 hours after transfection, cells were treated with IL33 (mouse) (rec.) (His) at the concentration as indicated for 8 hours, followed by measurement with a dual luciferase assay.