COL1A1 and atrial fibrillation: Gene expression analysis demonstrated that on both tissue culture plastic and deformable silicone membranes, primary AF cells maintained robust expression of the AF‐associated markers Col1a1,44Gdf10,45 the marker of sclerotome development, Pax1,48 and Cilp49 a gene recently reported by our group as enriched in the murine AF compared to the NP.50