CA9 and neoplasm: CA9 positive staining was rare in vehicle-treated Calu-3 tumours (Fig. 3A and B), suggesting that Calu-3 tumours are well-oxygenated, whereas cediranib-treated Calu-3 tumours showed significantly higher hypoxic fractions compared to the vehicle-treated control (P < 0.001; Fig. 3A and B), suggesting that cediranib treatment induced acute hypoxia, consistent with reduced perfusion.