Fig 5a shows all senescence-associated proteins were higher in PD50 cells than PD20 cells, but no difference between PD50 cells and PD48-Cd3-PD2 cells, indicating chitosan-induced lifespan extending did not downregulate the proteins which are involved in tumor suppressor pathways. Furthermore, the soft agar assay showed that the chitosan-treated cells did not form colonies while the control HeLa cells formed colonies in soft agar (Fig 5b). Here, PAF1 is linked to neoplasm.