To examine whether the persistent elevation of Il6 mRNA is a cause for pressure overload–induced heart failure in Reg1−/− mice, IL-6 signaling was blocked using a monoclonal antibody against the IL-6 receptor (MR16-1) after TAC surgery.9 Control IgG or MR16-1 had no effect on cardiac chamber size and function and heart and lung weight in sham-operated Reg1+/+ and Reg1−/− mice (Figure IIE and IIF in the online-only Data Supplement). The gene discussed is IL6; the disease is heart failure.