LTA and Merkel cell skin cancer: MCPyV genome integrationwith MCC generally results in unaltered expression of the native sTantigen.90,105 Tumor regression in vivo was achieved withshort hairpin RNA-mediated elimination of MCPyV sT/LT antigen in MCCcell lines.105,106 These studies demonstrate thatMCC tumor cell growth in vitro and in xenograft models requires theexpression of MCPyV LT and sT antigens.