Interestingly, TNF is linked to upregulation of Purkinje cell protein-4 (PCP4), a putative regulator of calmodulin and Ca2+/calmodulin-dependent kinase II (CaMKII) signaling, within the His-Purkinje network and contributor to cardiac arrhythmias (40). This evidence concerns the gene TNF and chronic obstructive pulmonary disease.