We identified 38 human proteins significantly increased and 8 proteins decreased in MCV+ versus MCV– MCC samples, including SERPINB5, a reported tumor suppressor also known as mammary serine protease inhibitor (MASPIN) (27), and TRIM29, a ubiquitin E3 ligase that may act as a scaffold protein in the DNA damage response (28). Here, TRIM29 is linked to Merkel cell skin cancer.