library_construction_protocol: Mouse tumors and cerebellum were digested in 3.2 mg/ml collagenase IV (Worthington Biochemical Corporation, LS004209), 1 mg/ml Deoxyribonuclease I (Worthington Biochemical Corporation, LS002007) and 2 mg/ml soybean trypsin inhibitor (Worthington Biochemical Corporation, LS003587) in DPBS for 10 min at 37 °C while shaking to separate cells. Dissociated single cells were checked for viability using a ViaStain AOPI staining solution (Nexcelcom Biosciences, CS2-0106-5ML) and counted using a Cellometer Auto 2000 Viability Counter (Nexcelcom Biosciences). Any dead cells were removed afterwards using a Miltenyi Biotech Dead Cell Removal kit (130-090-101). CDNA libraries were prepared using the Chromium Next GEM Single Cell 3' Reagent Kit v3.1 (10x Genomics). For quality control, the libraries were tested using High Sensitivity D5000 ScreenTape and 4200 Tapestation system (Agilent Technologies).