Importantly, cancers with MYC activation are highly sensitive to HSP90 inhibitors such as PU‐H71, an ATP competitor similar in function to squamocin.[17b] As anticipated, we observed dose‐ and time‐dependent inhibition of cell viability by squamocin treatment in GC (AGS and MNK45) and CRC (SW480 and LOVO) cell lines, with IC50 was calculated in AGS (IC50 = 13.60 μg mL−1) and MNK45 (IC50 = 12.43 μg mL−1), SW480 (IC50 = 12.04 μg mL−1) and LOVO (IC50 = 13.72 μg mL−1), respectively (Figure S7C,D, Supporting Information). This evidence concerns the gene MYC and cancer.