PTEN and neoplasm: In vivo studies in mice revealed that both mutations of Pten that abolish lipid phosphatase activity, C124S and G129E, have a dominant negative effect over wild type Pten in a heterozygous setting (Pten+/C124S or Pten+/G129E), rendering mice with an amplified tumor spectrum compared to mice affected by Pten loss of heterozygosity (Pten+/-), an effect that can be explained by PTEN heterodimerization [26].