LY6K and head and neck squamous cell carcinoma: Several investigations found overexpression of LY6K in several human malignancies, such as head and neck squamous cell carcinomas and breast, lung, and oesophageal cancers (de Nooij-van Dalen et al, 2003; Scanlan et al, 2004; Lee et al, 2006; Ishikawa et al, 2007; Choi et al, 2009; Kono et al, 2009).