Natural Killer (NK) cells, integral to the innate immune system, are notable in cell therapies because for their applicability in allogeneic treatments, distinguishing them from T cells typically employed in conventional cell therapies. However, their limited half-life poses a challenge for therapy. Although attempts to leverage feeder cells are common, safer methods are needed to mitigate the associated risks. In our study, an upregulation in the expression of 4-1BBL in Colo-205 cells under extracellular stresses such as hypoxia and cytochalasin D was observed. This enhanced binding to the 4-1BB receptors on NK cells promotes proliferation in NK cells. Elevated CD56 expression of a marker strongly linked to NK cell proliferation in co-culture further supports this process. Applying extracellular stressors, specifically hypoxia and cytochalasin D, to Colo-205 cells successfully tailored feeder cells, significantly enhancing NK cell proliferation.