PLN and cardiomyopathy: A key hallmark of PLN-R14del cardiomyopathy in humans and mice is the occurrence of detrimental cardiac SR clusters, as evidenced by strong perinuclear PLN staining in R14Δ/Δ cardiomyocytes.5,9 In vehicle-treated R14Δ/Δ mice, PLN clusters were highly prevalent with 17.7 ± 1.3 cluster-positive cells per 0.1mm,2 whereas such clusters were not observed in WT mice (Figure 4A and B).