ACAN and atrial fibrillation: Lastly, AF cells were exposed to acute (30 minutes) 6% CTS at 2.0 Hz showed a significant increase in the expression of the ECM genes Acan and Prg4 (6 hours and 2 hours postloading, respectively; fold change (Acan) = 2.4 ± 0.12, fold change (Prg4) = 3.2 ± 0.89) compared to unloaded controls (Figure 8A).