In keeping with the well-characterized loss of t-tubule structure during heart failure, we identified that mRNA for junctophilin-2 (Jph2), which is a major cardiac t-tubule anchoring and structural protein6, 7, was significantly downregulated in mouse hearts lacking Csrp3−/−, as well as hearts from mice overexpressing CnA, and in both scar and remote regions of mouse hearts 2 weeks after MI surgery. The gene discussed is PPP3CA; the disease is heart failure.