We examined the effect of the CAIX inhibitor 4-(3′(3′′,5′′-dimethylphenyl)-ureido)phenyl sulfamate (S4) on the tumor microenvironment in a laryngeal tumor model by analyzing proliferation, apoptosis, necrosis, hypoxia, metabolism and CAIX ectodomain shedding. The gene discussed is CA9; the disease is neoplasm.