Similarly to Schwann cells induced axonal regeneration upon nerve injury, NGF, BDNF, NT3 or IGF-II produced by cancer cells sustain cancer growth and PNI through the expression of neurites chemoattractant and guidance molecules associated with poor prognostic outcome (netrin, semaphorins, ephrins, and Slits) [120,121]. The gene discussed is IGF2; the disease is cancer.