Infection of fibroblasts from old mice with lentiviral particles containing a DNA sequence that codes for a shRNA targeting Zeb2 had no significant effect on Zeb2-NAT RNA (Supplementary Fig. 5a), but resulted in a robust decrease of total Zeb2 RNA (Supplementary Fig. 5b), and Zeb2 protein (Supplementary Fig. 5c). This evidence concerns the gene ZEB2 and infection.