Merkel cell carcinoma (also known as a "Cutaneous apudoma," "Primary neuroendocrine carcinoma of the skin," "Primary small cell carcinoma of the skin," and "Trabecular carcinoma of the skin") is a rare and highly aggressive cancer in which malignant cancer cells develop on or just beneath the skin and in hair follicles. The majority of Merkel cell carcinomas appear to be caused in part by a virus, Merkel cell polyomavirus or MCV. Direct evidence for this comes from studies showing that inhibition of MCV proteins causes MCV-infected Merkel carcinoma cells to die but has no effect on tumor cells from Merkel cell carcinomas that are not infected with the virus...