PGF and lung cancer: Insulin-like growth factor 1 (IGF1) was found to initiate self-renewal of lung cancer stem cells in dormant lung tumors via the activation of a PI3K/Akt/β-catenin pathway and production of the angiogenic factors chemokine (C-X-C motif) ligand 1 (CXCL1) and placental growth factor (PlGF) [59].