OBSCN and atrial fibrillation: The presence of severe AF in Obscn-ΔIg58/59 mice (16) and the prominent alterations in key regulators of intracellular Ca2+ cycling identified in our phospho-proteomic screen (17) prompted us to further evaluate Ca2+ homeostasis in atrial cardiomyocytes isolated from sedentary Obscn-ΔIg58/59 male animals at 6 and 12 months.