hCAIX-IN-23 (Compound 27) is a human carbonic anhydrase ( hCA ) inhibitor with K i values of 10.4 and 8.5 nM for hCA IX and hCA XII , respectively. In addition to inhibiting hCA activity, hCAIX-IN-23 releases NO , exhibiting dual antitumor activity. hCAIX-IN-23 induces apoptosis by regulating mitochondrial caspase activity and the ferroptosis pathway ( ferroptosis ) through the downregulation of hCA IX and iron-regulatory protein expression. hCAIX-IN-23 is useful for renal cancer research.