The EL-4 tumour cells were counted using a Burker chamber, centrifuged in the growth media for 5 min at 125x g-force, and the supernatant was removed. 10.0 ± 0.1 million cells were suspended in 200 µl of culture media and transferred into a 5 mm NMR test tube for experiments. For experiments on lysed cells, this cell suspension was double freeze-thawed in liquid nitrogen. The NMR tube (containing either lysed or intact cells) was then placed in the NMR magnet and equilibrated at 310 K. At the end of each experiment the number of cells was quantified using a Bradford protein assay with a specific calibration line, and was measured to be 10 ± 0.1 million in all experiments.