PTK2 and atrial fibrillation: Mechanical stimulation of non-degenerate AF cells with 20 minutes CTS (10% strain, 1.0 Hz) led to a significant increase in phosphorylated FAK (tyr397), similar to that reported above (77% increase+/−15%) in FAK phosphorylation versus total FAK protein, when compared to levels at 5 minutes CTS (p≤0.05) (Figure 4).