To confirm the role of DHODH inhibition in the reduced viability of Ewing's sarcomas induced by K‐234 and its derivatives, we investigated the inhibitory effects of these compounds against DHODH enzymatic activity and compared its 50% inhibitory concentration (IC50) values with their 50% growth inhibition concentration (GI50) values for A‐673 cells. This evidence concerns the gene DHODH and Ewing sarcoma.