Figure 1. Human Recombinant TGF-beta 1 Is Bioactive

The biological activity of Human Recombinant TGF-beta 1 was tested by its ability to induce luciferase expression in a SMAD/TGF luciferase reporter cell line. The EC50 is defined as the effective concentration of the agonist at which luminescence is 50% of maximum. The EC50 in the example above is 0.52 ng/mL. Normalized mean % of 3 replicate wells is shown for each data point. Each assay is calibrated with a Non-WHO International Reference Material (NIBSC code: 89/514). EC50 is assay-specific; titrations should be performed to determine the optimal concentration for the intended application.

Figure 2. Human Recombinant TGF-beta 1 Has High Purity

Human Recombinant TGF-beta 1 (1 μg) was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie Blue staining. Human Recombinant TGF-beta 1 is a homodimer of 12.8-kDa subunits with a predicted molecular mass of 25.6 kDa.

Figure 3. Sources of TGF-beta 1 from STEMCELL Technologies and a leading competitor demonstrate similar biological activity in the luciferase assay

The biological activity of TGF-beta 1 was determined using a luciferase reporter cell line responsive to SMAD2/3. Luciferase activity was measured 24 hours after application of the TGF-beta 1 dilution series to the cells and the EC50 was determined by four-parameter curve fitting. EC50 values of the three TGF-beta 1 sources were: Hu TGF-beta 1(Cell Culture Ready) = 1.182 ng/mL; Hu TGF-beta 1 = 1.109 ng/mL; Competitor TGF-beta 1 = 1.649 ng/mL. The EC50 is defined as the effective concentration of the growth factor at which relative luminescence is 50% of maximum. There were no significant differences in the EC50 values between samples, and all were within the normal biological variability of the assay.