A 50 µL plasma standard was prepared in a 1.7 mL microcentrifuge tube using 20X working stock solution. 100 µL of acetonitrile containing taxol (internal standard) (1.25 µg/mL) was added to each tube. Tubes were vortexed for 20 seconds and incubated at room temperature for 10 minutes. Tubes were centrifuged at 15,000 rpm for 3 minutes. 100 µL of each supernatant was transferred to a glass autosampler vial insert in a 2 mL glass autosampler vial. Samples with concentrations above the maximum concentration of the standard curves were diluted appropriately with blank human plasma to fit within the standard curves, and concentrations were appropriately adjusted for the dilution. Tissue biodistribution. Tissues were weighed on a Mettler Toledo XP205 DeltaRange milligram balance and placed in 2 mL beadmill tubes containing 2.8 mm ceramic beads (Fisherbrand, #15-340-154, Pittsburg, PA). A 2X volume of ice-cold PBS was added to each sample. Tissues were homogenized with a Fisherbrand Bead Mill 24 (Pittsburg, PA) at the following settings: speed, 5; time, 10 sec; cycle, 3; dwell, 3. 50 µL aliquots of the homogenates were processed as described above and analyzed by LC-MS/MS. Samples with concentrations exceeding the highest concentration on the standard curves were diluted with mouse plasma to fit within the standard curve and concentrations were appropriately adjusted to account for the dilution.