TP53 and neoplasm: Tumors from Dmp1-/- or Dmp1+/- (Eμ-Myc, K-RasLA, HER2 mutant) mice rarely showed mutations, deletions, or silencing of p19ARF or p53, suggesting that Dmp1 is a critical regulator of the ARF-p53 tumor suppressor pathway in vivo [14,34,35,39,48,49,50,51].