To track extracellular vesicles Nalm-6 CD19− and glioblastoma U87 cell lines were transduced with lentiviruses coding for two exosome-specific reporter proteins—tetraspanin CD63 fused with nanoluciferase (CD63-nluc) or eGFP (CD63-eGFP) (Supplementary Figure 2C; Supplementary Figure 3A)25. Here, CD63 is linked to glioblastoma.