ATOH1 and Merkel cell skin cancer: MCC also expresses other markers of Merkel cells including cytokeratin 8 (KRT8) and the transcription factors SRY-box transcription factor 2 (SOX2) and atonal BHLH transcription factor 1 (ATOH1) (15–17), whose transcriptional activity is essential for survival of MCC cells (7).