Table 2 compares the CellTiter‐Blue assay GI50 values (HEK‐293 and MDA‐MB‐231 human cell lines, 24 h incubation time) and colony formation data IC50 values (MCF‐7 breast cancer cells) with the Hsp90 ATPase activity IC50 values for each of the compounds. This evidence concerns the gene HSP90AB1 and breast carcinoma.