Upregulation of the heme biosynthesis pathway caused by an increase of UROD expression is observed in pediatric AML samples with high MYCN expression.28 A recent study indicated the useful application of the knockdown of the heme biosynthesis pathway against Bcl-2 inhibitor resistance in AML cells.29 In this study, AML cell lines showed strong sensitivity to COX15-targeting sgRNAs, unlike chronic myeloid leukemia (CML) and sarcoma cell lines. Here, UROD is linked to sarcoma.