CA9 and neoplasm: To assess whether BxPC3 5xHRE/GFP fluorescence intensity measured using IVFM is representative of hypoxia throughout the tumor, we compared the mean tumor cell GFP fluorescence intensity in vivo (using IVFM) to the tumor hypoxic fraction from 11 different tumors, immunofluorescence-stained for both PIMO and CA9 (Fig. 6C).