Our studies were performed as previously described [5 (link)–8 (link)]. The slides were counterstained with 4,6-diamidino-2-phenylindole (Pierce, Rockford, IL, USA). We also used antibodies to desmoplakins (DP)-I–II (mouse monoclonal multi-epitope cocktail; Progen Biotechnik [Heidelberg, Germany], cat no. 65146). We utilized antibodies to armadillo repeat gene deleted in velo-cardio-facial syndrome (ARVCF) (polyclonal antibody, source guinea pig, tested in human and bovine; Progen Biotechnik, cat no. GP155); for its secondary, we used Alexa Fluor- 555 goat-anti-guinea pig from Molecular Probes/ Life Technologies/Thermo Fisher Scientific (Waltham, MA, USA). We also utilized an antibody to plakophilin-4 (p0071); Progen Biotechnik, cat no. 651166) and a mouse monoclonal antibody for myocardium-enriched zonula occludens-1- associated protein (MYZAP) [Progen Biotechnik, cat no. 651169]. As a secondary antibody for DP-I–II, the p0071 and the MYZAP, we utilized Texas red-conjugated goat anti-mouse IgG from Thermo Fisher. The samples were consistently run with positive and negative controls. We classified our findings as negative (−), weakly positive (+/−), positive (++) and strongly positive (+++).