TERF1 and neoplasm: To validate these results using an independent strategy to inhibit TRF1, as well as to assess the effect of TRF1 abrogation in already established K-Ras-induced lung tumors, we downregulated Trf1 expression by using shRNA technology in three K-RasΔ/G12Vgeop53−/− mouse cancer cell lines derived from three independent mouse lung carcinoma lesions and assessed the effects on tumor growth using two independent allograft experiments.