Cyclic stretch increases TLR4 promoter activity. Upper panel, constructs of TLR4 promoter gene. Lower panel, quantitative analysis of TLR4 promoter activity. Cardiomyocytes were transiently transfected with pTLR4-Luc by gene gun. The luciferase activity in cell lysates was measured and was normalized with renilla activity (n = 3 per group). *P < 0.001 vs. control. **P < 0.001 vs. 2 h.