The tumour-related expression pattern of CA IX is principally determined by a strong activation of CA9 gene transcription via a hypoxia-inducible factor (HIF), which binds to hypoxia responsive element (HRE) localised in the minimal CA9 promoter proximal to transcription start site at −10/−3 position (Wykoff et al, 2000). Here, CA9 is linked to neoplasm.