IL24 (interleukin 24) is a cytokine that belongs to IL10 family. This protein can induce apoptosis selectively in various cancer cells, including ECV304. Thus, inhibition of cell proliferation assay of IL24 was conducted using ECV-304 cells. Briefly,?ECV-304 cells were seeded into triplicate wells of 96-well plates at a density of 2,000 cells/well and allowed to attach overnight, then the medium was replaced with serum-free standard 1640?prior to the addition of various concentrations of IL24. After incubated for 48h,?cells were observed by inverted microscope and cell proliferation was measured by Cell Counting Kit-8 (CCK-8). Briefly, 10μL of CCK-8 solution was added to each well of the plate, then the absorbance at 450nm was measured using a microplate reader after incubating the plate for 1-4 hours at 37°C. Inhibition of ECV-304 cells proliferation after incubation with IIL24 for 48h observed by inverted microscope was shown in Figure 1. Cell viability was assessed by CCK-8 (Cell Counting Kit-8 ) assay after incubation with various concentrations of IL24 for 48h. The mean OD value of ECV-304 assessed by CCK-8 was shown in Figure 2. It was obvious that IL24 significantly decreased cell viability of ECV-304 cells.