PTPN11 and neoplasm: 65,66 showed that tyrosine phosphatase Shp2 prevents apoptosis in tumour stem cells by activating Erk. The expression of gain of function (GOF) mutation Shp2-E76K, the most common and active ptpn11mutation found in leukaemia and solid tumours, suppresses the apoptosis pathway 67. Shp2-D61Y or Shp2-E76K-expressing hematopoietic cells also reduce apoptosis, as indicated by Annexin-V staining results, and they produces increased progenitor colonies after 48 hrs in minimal media compared with cells transduced with an empty vector or wildtype of Shp2 68.