Therefore, two pathways underlie the function of this piRNA in fibrosarcoma oncogenesis by RRM2 targeting: RRM2 down-regulation results in failure of dNTP catalysis, leading to inhibition of cell proliferation owing to the lack of DNA synthesis; and RRM2 repression disrupts RRM2-mediated Bcl-2 regulation [65]. This evidence concerns the gene RRM2 and fibrosarcoma.