PTPN11 and neoplasm: Our study has demonstrated sustained or upregulated PI3K pathway activation upon MAPK pathway inhibition with Trametinib (MEK1/2 inhibitor) or SHP099 (SHP2 inhibitor), as well as sustained or upregulated MAPK pathway activation upon PI3K pathway inhibition via Omipalisib (p110α/β/δ/γ and mTORC1/2 inhibitor), in PDAC tumor cell lines.