Figure 8.

Internalization of ¹²⁵I-labeled EGF in GFP–CALM–expressing cells. (A) COS-1 cells transfected with GFP (mock; ○), GFP–CALM (▴), GFP–414–652 (▵), or GFP–1–413 (●) were incubated with 2.0 ng/ml ¹²⁵I-labeled EGF for 1–10 min, and the amount of surface-bound and internalized radioactivity was determined as described in MATERIALS AND METHODS. The rate of internalization is expressed as the ratio of internalized and surface ¹²⁵I-labeled EGF for each time point. (B) Internalization rates are averaged from four experiments performed as described in A. The rates are expressed as the percent of internalization rates in mock-transfected cells.