Colony formation assay results also showed that the number of colonies in the E2F1-OE group was significantly lower than that in the vector-control group, while the number of colonies in the E2F1-KD group was significantly higher than that in the NC-KD group (p < 0.05, Figure 8D), indicating that the upregulation of E2F1 can suppress tumor cell clonogenicity. Here, E2F1 is linked to neoplasm.