CA9 and cancer: Among the emerging strategies in cancer therapy, targeting human carbonic anhydrases IX and XII (hCA IX and hCA XII) has gained considerable attention because cancer cells are primarily dependent on these enzymes for their survival.4–6 The hCA IX and hCA XII are involved in pH regulation and various metabolic processes in hypoxic tumours, in which the vasculature system of tumour mass is unable to meet the oxygen demand of rapidly proliferating cancer cells.