It worth noting that as CAIX expression, which is trans-activated by hypoxia inducible factor-1α [51], has been reported in increasing cases of other cancers, such as lung, cervical, ovarian, esophageal, breast, prostate, bladder, and head and neck squamous cell carcinomas [52]–[54], the human CAIX antibodies discovered in this study will become very valuable reagents and be evaluated for their ability against different types of cancer through not only each above-mentioned mechanism but also their newly discovered carbonic anhydrase inhibitory effects. Here, CA9 is linked to head and neck squamous cell carcinoma.