In this study, we thus applied IgG fractions from patients with typical PV and PF and one atypical case of PV and evaluated (i) the potency to induce pemphigus hallmarks such as Dsg3 depletion and keratin retraction, (ii) their impact on the activity of specific signaling events and (iii) the relevance of these signaling events for loss of cell cohesion. The gene discussed is DSG3; the disease is acquired polycythemia vera.