Plasmid vectors (pCMV6) of TGC-specific AIs and Native were purchased from Origene (Table S2). All proteins were expressed in a suspension-adapted HEK293 cell line (ExPi293F, Thermo Fisher). Cells, growing in deep 6-well blocks, were transfected in triplicate at a density of 1.0 × 107/ml using ExpiFectamine™ 293 according to the manufacturer’s instructions. Following transfection, the cells were grown at 37 °C by shaking in 5% CO2, for 48 hours. The conditioned media, containing secreted protein, were harvested by centrifugation at 1000 rpm for 5 minutes. The clarified media from each of the three replicates for each expression vector were pooled and stored at −20 °C. Each transfection was performed in duplicate, on separate days, and the conditioned media was analyzed separately by Western blot analysis.