Lack of integrin β5 in Merkel cell carcinomas and derived cell lines is frequently associated with Merkel cell polyomavirus positivity.

Merkel cell carcinoma (MCC) is a rare but aggressive neuroendocrine skin neoplasia. The merkel cell polyomavirus (MCPyV), a double-stranded DNA tumor virus was discovered in 2008. It is found in approximately 80% of human MCC and is suspected to play a role in MCC development [1]. Both, small tumor and the aminoterminal moiety of the large tumor antigen, were found to be expressed in MCPyV-positive MCC [2]. Merkel cells are usually scattered in the basal cell layer of the epidermis along the dermo-epidermal junction [3].