PTN and cancer: Furthermore, 21 mitogenic growth factors were detected including pleiotrophin, macrophage colony‐stimulating factor 1 (CSF1), transforming growth factor beta, and those produced by cancer‐associated fibroblasts; proepidermal growth factor (EGF), insulin‐like growth factors I (IGF1) and II, and platelet‐derived growth factors C (PDGF‐C) and D (Table 1).