We took advantage of several established MCC cell lines [23,24] with either high ATOH1 expression (MCC1 and MCC6, derived from less aggressive tumors) or low ATOH1 expression (MCC13, MCC14.2, and MCC26, derived from highly aggressive metastatic tumors; Figure S4A and S4C). Here, ATOH1 is linked to Merkel cell skin cancer.