FMOD and atrial fibrillation: Fmod, an accepted AF‐specific marker in rodent (Leung, Tam, Chan, Chan, & Cheung, 2011; Smits & Lefebvre, 2003), was expressed in both genotypes, but its immunostaining signal was weaker in Tnmd−/− OAF cells compared with WTs (Figure S2b,g).