PTPN11 and osteosarcoma: We infected U2OS osteosarcoma, MDA-MB-468 mammary gland adenocarcinoma, A549 pulmonary adenocarcinoma and MDA-MB-231 breast cancer cells with retroviruses encoding the expression of VHL, aNSa1, VHL-aNSa1, aCS3 or VHL-aCS3, and monitored the endogenous SHP2 levels (figure 1c–f).