With regard to SHP2, Ruess et al. have revealed that knockout of the PTPN11 gene in KRAS mutant human ductal adenocarcinoma (PDAC) cells results in a reduction in cell proliferation and PTPN11-knockout cells are uniquely susceptible to mitogen-activated protein kinase (MEK) inhibitors [20]. Here, PTPN11 is linked to invasive ductal breast carcinoma.