And, it has been generally accepted that the hypermethylated status of the promoter CpG islands represents the long-term transcription-silencing state of the genes [11-13].Other researches have also offered the evidence that RASSF1 stimulation of lung cancer cell proliferation depends on IGFBP-5 and PIWIL1 expression levels [14]. The gene discussed is PIWIL1; the disease is lung cancer.