CLU and esophageal squamous cell carcinoma: CLU is described as being overexpressed in several types of cancers including colon, breast and lung cancer [37], yet a down-regulation has been found in esophageal squamous cell carcinoma, in some pancreatic, prostate or colon cancers and in HPV-negative squamous cell carcinoma of the head and neck [37,46,47], suggesting a pro-survival or a pro-apoptotic function.