Expression of SLC7A1/CAT-1, the predominant arginine importer in primary neuroblastoma tumors (Supplementary Figure S4B) and in the 4 selected neuroblastoma cell lines (Supplementary Figure S4C), was variably affected by BCT-100 exposure in a cell line- and concentration-dependent manner in vitro (Supplementary Figure S4D–E). The gene discussed is SLC7A1; the disease is neuroblastoma.