EP400 and Merkel cell skin cancer: Since ST binds and potentiates MYCL function through the ST-MYCL-EP400 complex (15), we suspected that viral antigen inactivation might also upregulate class I. To explore this, we transduced another established MCPyV+ MCC line, WaGa, with an shRNA targeting shared exons of ST and LT, leading to inactivation of both viral antigens.