NGF and cancer: This hypothesis is consistent with a number of previous and recent studies showing that NGF promote differentiation of cultured tumor cells and that single/repeated in vivo subcutaneously [17, 22, 72, 73], intracerebrally [5, 74], intranasally [75], topically [11–13, 76–79] and orally [80] NGF administered or even endogenously-induced/released NGF [73] do not cause uncontrolled cell proliferation nor lead to cancer cell generation.