L1CAM and neoplasm: In particular, we found: (1) a group of cells/nuclei in FN-RMS that express interferon response genes such as ISG15 and IFIT1-3 (“IFN” cluster; 1.5% of total cells/nuclei); and, (2) a tumor subpopulation in FP-RMS tumors that expresses neuronal marker genes including DCX, L1CAM, SYP, and CHGA (‘neuronal’ cluster; 1.4% and 4.8% of total cells/nuclei from PAX3::FOXO1 and PAX7::FOXO1 FP-RMS, respectively, Fig. 4A, S4A and S4B).