Germline and somatic PTPN11 mutations in human disease. A, Location of mutated residues in the three-dimensional structure of SHP-2 in its catalytically inactive conformation (green, N-SH2 domain; cyan, C-SH2 domain; pink, PTP domain). Residues affected by germline (left) or somatically acquired (right) mutations are shown with their lateral chains colored according to the proposed classification (red, group I; yellow, group II; green, group III; cyan, group IV; orange, group V; violet, group VI; blue, unclassified). B, In vitro phosphatase assay of wild-type and mutated SHP-2 proteins. The C459G mutant is a catalytically inactive protein used as negative control. Activity was measured as picomoles of phosphate released, with the use of pNPP as substrate in basal (white bars) and BTAM peptide-stimulated (black bars) conditions. Values are means ±SDs of at least four independent experiments and are normalized to unstimulated wild-type SHP-2.