NGF and neoplasm: MAPKs are stimulated by different mediators including growth factors (platelet-derived growth factor (PDGF), epidermal growth factor (EGF), and nerve growth factor (NGF)) [11], insulin [12], thrombin [13], angiotensin II [14], phorbol ester-type tumour promoter, Ca2+ [15], hydrogen peroxide [16], arachidonic acid [17], oocyte maturation activators [18], osmotic stress [19], UV radiation [20], activators of protein kinase C [21], T-cell antigen stimulator [22] and cytokines, including tumour necrosis factor (TNF) and interleukin 1β (IL-1β) [23].