TP53 and neoplasm: Moreover, long-term lack of telomerase in mice leads to telomere shortening and dysfunction, and promotes oncogenesis in a certain condition such as lack of tumor suppressors p53 [34, 39-43] or DNA mismatch repair protein MSH2 [44] or in the presence of telomeric repeat binding factor TRF2 overexpression [45], and also shifts the tumor spectrum of p53 mutant mice to include more epithelial cancers [42].