CNPY2 and atrial fibrillation: Taking in account observed significant elevation of CNPY2 in mouse AF and liver tumors associated with increase in numerous cytoskeletal and ER-related proteins, low expression in non-treated and surrounding livers, and a known CNPY2 ability to suppress proteolysis promoting ER stress and stabilize actomyosin complexes [10], we proposed that it may play an important role in the processes of tumor growth, cell proliferation, survival, invasion and metastasis.