AGT and sick sinus syndrome: The molecular basis underlying how TRPM7 is incorporated into Ang II-mediated TGF-β1/Smad signaling to direct the development of SSS has not been well defined, although one study proposed that TRPM7 was potentially required in TGF-β-induced fibrogenesis in human atrial fibrillation [26] and another study showed that TRPM7 mediated TGF-β1-elicited collagen expression in hepatic stellate cells [27].