PTPN11 and leukemia: Mostly, NS mutations lead to constitutive active SHP2, and in particular, the D61G substitution (PTPN11D61G) results in a 10-fold increase of basal SHP2 activity, while the leukaemia-causing D61Y change (PTPN11D61Y) induces 20-fold SHP2 basal activity [66].