Two candidate markers for MCC, atonal BHLH transcription factor 1 (ATOH1) and transcription factor AP-2β (TFAP2B), and one candidate marker for SCLC, carcinoembryonic antigen cell adhesion molecule 6 (CEACAM6), were tested using immunostaining. The gene discussed is CEACAM6; the disease is Merkel cell skin cancer.