Figure 3. Effect of electrical stimulation on LMNAR225X/WT dermal fibroblasts. (A-D) Immunofluorescence showing typical nuclear morphologies of control and LMNAR225X/WT dermal fibroblasts before and after electrical stimulation. (E) Effects of electrical stimulation on the percentage of control and LMNAR225X/WT dermal fibroblasts with nuclear blebs. (F) Effects of electrical stimulation and U0126 (ERK1/2 pathway blocker) on the apoptosis of control and LMNAR225X/WT dermal fibroblasts. The application of U0126, a highly selective blocker of the MEK1 pathway, nearly completely abolished the apoptotic effects of electrical stimulation on LMNAR225X/WT dermal fibroblasts. (G-H) Electrical stimulation-activates mitogen-activated protein kinases (MAPK) pathway in iPSC-CM: (G) MEK1 and (H) extracellular signal-regulated protein kinases 1 and 2 (ERK1/2) in LMNAR225X/WT dermal fibroblasts, but not in control fibroblasts. *p- value <0.05.