Although ARE-Lux with FoxH1 co-expression is often used as a Smad2-specific reporter (269, 270) based on the activity observed in Smad2−/− mouse embryonic fibroblasts (264), it is activated by TGF-β in SMAD2 knockout A549 human lung adenocarcinoma cells (271). The gene discussed is SMAD2; the disease is lung adenocarcinoma.