MRTFB and Merkel cell skin cancer: We had previously shown that the expression of CCL17 and IL33 is enhanced in MCPyV-positive MCC tumors and MCC cell lines (including MKL2 MCC cells), compared to virus-negative tumors and cell-lines, and that the CCL17 and IL33 promoters are activated by MCPyV MKL2 [41,42].