MUC1 and skin squamous cell carcinoma: Immunohistochemically, the tumor cells in cSCC are positive for immunolabeling with anti-p63, anti-p40, epithelial membrane antigen (EMA), anti-CK5/6, and panCK/CK AE1/AE3 antibodies (a cytokeratin cocktail with a high molecular weight) [1,7,31,32].