TBZT as an inhibitor of CA9. ( A) To validate predictions by PharmDB analysis for SCC, TBZT is tested for inhibitory activity against its potential targets, CA isozymes (CA1, CA2, and CA9). ( B) In vitro inhibition of TBZT and the AZA control against CA isoforms (i.e., 1, 2, and 9). ( C) Cellular levels of CA9 in the SCC cell line, HCC-1588, under normoxic and hypoxic conditions. ( D) The effect of TBZT on cell death was monitored by caspase-3 activation. (E) HCC-1588 cells, transfected with an empty vector (EV) or CA9, were treated with TBZT under normoxic and hypoxic conditions.