BAG3 and cardiomyopathy: Transgenic expression of P209L BAG3 in the mouse heart induced protein aggregates, with sequestration of endogenous WT BAG3 as well as sarcomere-associated proteins such as desmin, α-actinin, and myopodin (SYNPO-2) in aggregates, provoking sarcomere disruption and cardiomyopathy (22).