Co-treatment with GCV + ATO reduces tumor volume in a xenograft model of NPC A) Overview of tumor xenograft model and treatment regimen. B) Growth curve of the average tumor volume of each treatment group. Tumor volumes were measured by a blind investigator and compared to starting volumes as determined by the L*W2/2 formula. C) Comparative ending tumor volume as a percentage of baseline measurement. (*) denotes p < 0.05; (**) denoted p < 0.01; (***) denotes p < 0.005.