Lactoferrin (LTF), a member of the transferrin family of iron-binding glycoproteins, is a multifunctional protein predominantly secreted by exocrine glands and immune cells. It exerts potent iron-sequestering activity to deprive pathogens of essential iron, mediating broad-spectrum antimicrobial effects. Beyond innate immunity, LTF exhibits robust antiproliferative and proapoptotic properties in malignant cells: it modulates cell cycle checkpoints to arrest proliferation and activates caspase-dependent apoptotic signaling pathways, inducing programmed cell death in cancer cells. Additionally, LTF regulates immune responses and anti-inflammatory processes, making it a promising candidate for anticancer and antimicrobial therapeutic development. To test the effect of LTF on cell apoptosis, HCT116 cells were seeded into triplicate wells of 96-well plates at a density of 4,000 cells/well and allowed to attach overnight, then the medium was replaced with various concentrations of recombinant bovine LTF diluted with 5% serum standard DMEM. After incubated for 72h,?cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10 μl of CCK-8 solution was added to each well of the plate, then the absorbance at 450 nm was measured using a microplate reader after incubating the plate for 1-4 hours at 37 ℃. Cell viability was assessed by CCK-8 (Cell Counting Kit-8 ) assay after incubation with recombinant bovine LTF for 72h. The result was shown in Figure 1. It was obvious that LTF significantly decreased cell viability of HCT116 cells. The ED50 of recombinant bovine LTF is 2.91 μg/ml.