II-B08, also known as PTP Inhibitor XXXI, is a cell-permeable SHP2 inhibitor (IC50 = 5.5 μM). II-B08 blocks growth factor stimulated ERK1/2 activation and hematopoietic progenitor proliferation, providing supporting evidence that chemical inhibition of SHP2 may be therapeutically useful for anticancer and antileukemia treatment. X-ray crystallographic analysis of the structure of SHP2 in complex with 9 reveals molecular determinants that can be exploited for the acquisition of more potent and selective SHP2 inhibitors.