POU5F1 and neoplasm: Furthermore, we evaluated the tumorigenesis potential of Oct3/4-transfected BC cells in vivo, using a nude BALB/c mouse model, and observed that the Oct3/4 activation and proportion of Oct3/4 expression is associated with a marked increase in the tumor-seeding potential (initiation), recurrence and metastasis compared to cells with inactive Oct3/4 (Figure 2B–E).