PTEN and neoplasm: In the case of the PTEN (Papa et al, 2014), FBXW7 (Welcker & Clurman, 2008) and SMAD4 (Miyaki & Kuroki, 2003) genes, as well as several other tumor suppressors (de Vries et al, 2002; Hanel et al, 2013), a frequent mechanism of inactivation is through point mutations that reoccur at the defined residues and act dominantly on the molecular level.