PTPN11 and myeloproliferative disorder: Kawashima et al. demonstrated that metformin treatment activated PP2A in myeloproliferative neoplasm (MPN) cells to suppress the oncogenic kinase JAK2V617F by increasing reactive oxygen species levels leading to the inhibition of SHP-2, a positive regulator of JAK2V617F; furthermore, the results indicated that metformin suppressed phosphorylation of the PP2Ac at Tyr307 in a dose-dependent manner.