Frankincense essential oil-suppressed pancreatic tumor growth in a heterotopic xenograft mouse model. The xenograft mouse tumor model was established by subcutaneous implantation of 1 × 107 MIA PaCa-2 cells in 250 μl HBSS supplemented with 20% Matrigel™ into the flank of each mouse. Tumors were allowed to grow for 7 days. Mice were randomly assigned to receive either 100 μl PBS (control; 5 mice) or Fraction IV frankincense essential oil (30 μl essential oil plus 70 μl PBS; 6 mice). Treatment was administered through subcutaneous injection away from the tumors. (A) Tumor volumes measured in situ. Arrows indicate the time of tumor size measurement followed by frankincense essential oil treatment. (B) Tumor volumes calculated after the tumors have been removed from the experimental subjects at the end of experiments. Images were taken at the time of tumor harvest. * indicates statistical difference between PBS- and essential oil-treated groups (P < 0.05).