CA9 and breast cancer: This differential effect of CO2/HCO3– at the core and periphery of breast cancer organoids is abrogated when intra- and extracellular carbonic anhydrases are inhibited with acetazolamide but not when only extracellular carbonic anhydrases or CA9 are inhibited with AMB and FC5-207A, respectively (Fig. 6I-N).