library_construction_protocol: 10-30mg of tissue was cut from tumors and was input into the 10x Nuclei Isolation Kit (PN-1000494). Kit instructions were followed but lysis buffer incubation time was increased to 15 minutes to isolate quality nuclei. Mouse embryonic forebrain was isolated with the 10x Demonstrated Protocol CG000366 RevD, but lysis buffer incubation was decreased to 2 minutes. Nuclei were resuspended in nuclei buffer, counted via hemocytometer, and 10,000 were loaded onto the 10x Chromium Chip. Libraries were assessed via Agilent TapeStation and sent for sequencing at St. Jude's Hartwell Center on a NovaSeq 6000. Gene Expression libraries had 400 million reads with a 28-10-10-90 cycle configuration and ATAC libraries had 500 million reads with a 50-8-24-49 cycle configuration.