PTPN11 and leukemia: To assess whether the effect of matrine on leukemia cells is involved in the inactivation of Ras/Raf/ERK/MAPK signaling pathway, the expression of MEK, ERK1/2, phospho-MEK, phospho-ERK1/2 protein and the upstream adaptor molecules SHP2 and Shc were detected by Western blot.