CA9 and neoplasm: Recently, numerous studies suggest that the overexpression of Carbonic Anhydrase IX promotes the metastasis and the growth as well as the chemoresistance [43] of the tumor by the acidification of the extracellular matrix—therefore, as it is postulated, an inhibition of Carbonic Anhydrase IX protein can lead to the decreased invasiveness and to the cell death under the oxygen-deficient conditions [44,45].