All procedures involving animals were in accordance with the institutional animal welfare guidelines of Taipei Veterans General Hospital. 1000, 3000, and 10 4 cells were injected into the tail vein of SCID mice and/or nude mice (BALB/c strain) each aged 8 weeks. In vivo GFP imaging was visualized and measured by an illuminating device (LT-9500 Illumatool TLS equipped with excitation illuminating source [470 nm] and filter plate [515 nm]). The tumor size was measured with calipers and the tumor volume was calculated according to the formula (Length6Width 2 )/2. The integrated optical density of green fluorescence intensity was captured and then analyzed by Image Pro-plus software [29] .