CDKN2A and lung cancer: Several different signalling pathways play significant roles in lung cancer therapy, for example, Growth promoting pathways (Epidermal Growth Factor Receptor/Ras/ PhosphatidylInositol 3-Kinase),Growth inhibitory pathways (p53/Rb/P14ARF, STK11), Apoptotic pathways (Bcl-2/Bax/Fas/FasL),DNA repair and immortalisation genes.