FIGURE 3.

TβRIII undergoes down-regulation. HepG2 cells endogenously expressing TβRIII or COS7 cells transiently expressing TβRIII-FL or TβRIIIΔgag were bound and cross-linked with ¹²⁵I-labeled TGF-β1. Cells were placed at 37 °C for 1–24 h. Densitometry was performed using ImageJ, and values were normalized to β-actin. Data were fit to a single exponential decay function from which the time constant, τ, was determined. Data are representative of two or more independent experiments.