PTPN11encodes the SHP2 protein tyrosine phosphatase that activates the mitogen-activated protein kinase (MAPK) pathway upstream ofKRASand MEK.PTPN11/Shp2 somatic mutations occur frequently in Juvenile myelomonocytic leukaemia (JMML); however, the role of mutatedPTPN11in lung cancer tumourigenesis and its utility as a therapeutic target has not been fully addressed. We applied mass-spectrometry-based genotyping to DNA extracted from the tumour and matched the normal tissue of 356 NSCLC patients (98 adenocarcinomas (LUAD) and 258 squamous cell carcinomas (LUSC)). Further,PTPN11mutation cases were identified in additional cohorts, including TCGA, Broad, and MD Anderson datasets and the COSMIC database.PTPN11constructs harbouringPTPN11E76A, A72D and C459S mutations were stably expressed in IL-3 dependent BaF3 cells and NSCLC cell lines (NCI-H1703, NCI-H157, NCI-H1299). The MAPK and PI3K pathway activation was evaluated using Western blotting.PTPN11/Shp2 phosphatase activity was measured in whole-cell protein lysates using an Shp2 assay kit. The Shp2 inhibitor (SHPi) was assessed both in vitro and in vivo in aPTPN11-mutated cell line for improved responses to MAPK and PI3K targeting therapies. SomaticPTPN11hotspot mutations occurred in 4/98 (4.1%) adenocarcinomas and 7/258 (2.7%) squamous cells of 356 NSCLC patients. Additional 26PTPN11hotspot mutations occurred in 23 and 3 adenocarcinomas and squamous cell carcinoma, respectively, across the additional cohorts. MutantPTPN11significantly increased the IL-3 independent survival of Ba/F3 cells compared to wildtypePTPN11(p< 0.0001). Ba/F3, NCI-H1703, and NCI-H157 cells expressing mutantPTPN11exhibited increasedPTPN11/Shp2 phosphatase activity and phospho-ERK1/2 levels compared to cells expressing wildtypePTPN11. The transduction of thePTPN11inactivating mutation C459S into NSCLC cell lines led to decreased phospho-ERK, as well as decreased phospho-AKT in thePTPN11-mutated NCI-H661 cell line. NCI-H661 cells (PTPN11-mutated,KRAS-wild type) were significantly more sensitive to growth inhibition by the PI3K inhibitor copanlisib (IC50: 13.9 ± 4.7 nM) compared to NCI-H1703 (PTPN11/KRAS-wild type) cells (IC50: >10,000 nM). The SHP2 inhibitor, in combination with the PI3K targeting therapy copanlisib, showed no significant difference in tumour development in vivo; however, this significantly prevented MAPK pathway induction in vitro (p< 0.0001).PTPN11/Shp2 demonstrated the in vitro features of a driver oncogene and could potentially sensitize NSCLC cells to PI3K inhibition and inhibit MAPK pathway activation following PI3K pathway targeting.