Piperine reduces the level of Bcl-2 and increases the level of Bax-2 and this high Bax:Bcl-2 ratio leading to initiation of caspase 9/3 dependent apoptosis in lung cancer cells and piperidine along with maintaining high Bax:Bcl-2 ratio, it also down-regulates CD31 expression and inhibits the G1/S phase transition of the cell cycle. The gene discussed is CASP9; the disease is lung cancer.