PIK3CA and cancer: To illustrate this, we have extracted the I/O response RDSP of the PI3K/PTEN/AKT and MAPK pathways for different cancer cell lines using experimental data on the dose dependence of receptor activation (EGFR and PDGFR) and output signal (pAKT and pERK) on ligand concentrations (EGF and PDGF) (49, 54, 55).