PV is a complex autoimmune disease with Dsg3 being a central player in pemphigus acantholysis that likely is triggered by a collection of signaling pathways, including Src, p38 MAPK, EGFR, c-Myc, and Rho GTPases, downstream of PV-IgG targeting Dsg3 disruption4,17. Here, EGFR is linked to acquired polycythemia vera.