SELENBP1 and in situ carcinoma: To validate the proteomic results, Western blotting was performed to detect the expressional levels of SELENBP1 in an independent set of LCM-purified tissue samples including NBE, SM, AH, CIS and invasive LSCC, and immunohistochemistry was performed to detect the expressional levels of SELENBP1 in an independent set of archival tissue specimens including NBE, SM, AH, CIS, and invasive LSCC.