CHI3L1 and neoplasm: In the c-fms-rtTA/(TetO)7-CMV-Api6 spontaneous lung tumor mouse model, the average CHI3L1 concentration in BALF of doxycycline-treated mice with tumor (189.6±47.2 ng/ml) was ∼3-fold higher than that in BALF of doxycycline-untreated mice (69.6±16.6 pg/ml, p = 0.002, Figure 4B, upper left panel).