AQP1 and neoplasm: As expected, AQP1-expressing tumours are readily distinguishable from contralateral GFP-expressing cells in diffusion-weighted images acquired after induction (Fig. 4b), with the average diffusion-weighted signal intensity in AQP1 tumours decreasing by 39.4±6.5% after doxycycline injection compared with GFP controls (P=0.0155, n=5, pairwise t-test; Fig. 4c and Supplementary Fig. 5).