phosphatidylinositol 3-kinase signaling A series of reactions within the signal-receiving cell, mediated by the intracellular phosphatidylinositol 3-kinase (PI3K). Many cell surface receptor linked signaling pathways signal through PI3K to regulate numerous cellular functions. GO:0014065 PI 3-kinase cascade PI3K cascade PI3K signal transduction PI3K signaling biological_process phosphatidylinositol 3-kinase cascade phosphatidylinositol 3-kinase signal transduction phosphoinositide 3-kinase cascade phosphatidylinositol-mediated signaling