Transforming growth factor beta 1 or TGF-β1 is a polypeptide member of the transforming growth factor beta superfamily of cytokines. It is a secreted protein that performs many cellular functions, including the control of cell growth, cell proliferation, cell differentiation, and apoptosis.To test the effect of TGF-β1 on cell apoptosis, HepG2 cells were seeded into 96-well plates at a density of 4,000 cells/well with 5% serum standard DMEM including various concentrations of recombinant rabbit TGF-β1. After incubated for 48h, 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 1-2 hours at 37 ℃. Apoptosis of HepG2 cells after incubation with TGF-β1 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 recombinant rabbit TGF-β1 for 48h. The result was shown in Figure 2. It was obvious thatTGF-β1 significantly inhibit cell viability of HepG2 cells. The ED50 is 7.0 μg/ml.

Figure 2. Inhibition of HepG2 cells proliferation after stimulated with TGF-β1.