CA9 and neoplasm: These include increased expression of a hypoxic gene signature in 10 of 21 patients (Mehta et al, 2011), increased immunohistochemical staining for CA9 and HIF averaging a threefold increase in 9 of 21 tumours (DeLay et al, 2012) and increased, relative tumour hypoxia as analysed by high-resolution T2 and T2′ mapping (Hattingen et al, 2011).