NTRK1 and Merkel cell skin cancer: Therefore, considering the causative roles of MCPyV and MCPyV large T-antigen and the potential role of TrkA in MCC pathogenesis and progression, and the analogous nature of SV40 and MCPyV large T-antigens [26], we initiated a pilot study to determine whether alternative TrkAIII splicing may represent an oncogenic mechanism and potential therapeutic target in MCC.