In comparison, the CHI3L1 protein expression level was increased in one of three doxycycline-treated mice without tumor (+DOX, lane 5), indicating that CHI3L1 expression was elevated prior to tumor formation, and in all four doxycycline-treated CCSP-rtTA/(TetO)7-CMV-Stat3C mice with tumor (Lung cancer, lanes 7, 8, 9, and 10). This evidence concerns the gene CHI3L1 and lung cancer.